CHAPTER VIIDEFENSIVE MEASURES -- NEPTUNE OPERATION

PART IENEMY NAVAL DISPOSITIONS, 1944

Before pursuing the adventures of the assault forces,
the comprehensive measures executed for their protection
and support will be reviewed. The protection of NEPTUNE
from enemy counter action was essential to the success of
the operation. Allied forces were most vulnerable to enemy
counter action when they were embarked and at sea. Some
5,000 allied vessels, carrying approximately nine army divisions
with full combat equipment, were at sea at one time.1
These vessels were formed into some 75 convoys and groups,
passing along narrow coastal lanes, moving across the channel
through the narrow mineswept channels of the SPOUT2
or crowded into the congested confines of the assault area. Had
the enemy not been deterred by a comprehensive program of
defense, this enormous armada would have presented to enemy
air and naval forces a very profitable target.

Enemy naval forces available to attack NEPTUNE consisted
of two battleships (by D-day, both were seriously damaged),
two pocket battleships, one unfinished aircraft carrier, two
heavy cruisers, four light cruisers, thirty-seven seaworthy
destroyers, eighty-three torpedo boats, and some 200 U-Boats.3
In addition, the enemy had some 215 miscellaneous small war
vessels stationed in or near the channel.4

--410--

It was assumed that once the enemy was aware that the
Allies had committed themselves to the Normandy invasion, he
would expend his forces ruthlessly in an attempt to defeat
it. His heavy units in the north were not expected to be
used directly in the Channel area, except, possibly, as a
last desperate measure. They were likely, however, to make
diversionary sorties into the Atlantic. But his light surface
forces might be concentrated in the Channel against NEPTUNE.
These forces were expected to restrict their attacks to darkness
or periods of low visibility, and to operate primarily
on the assault and convoy flanks. Enemy U-Boats were expected
to concentrate rapidly in the Channel and its western approaches
and to operate without regard to loss. The enemy also maintained
a mine barrier along the continental coast line, and
was expected to undertake further offensive and defensive minelaying,
especially in sea areas around the U.K. assembly areas
and the assault areas, both by aircraft and naval minelayers.

The allied naval plan to defend NEPTUNE against the enemy
naval threat was:

To prevent distant enemy forces from moving toward the
approaches to the Channel,

To seal off both ends of the Channel, so that enemy
forces in its environs could not penetrate,

Within the Channel, to patrol the flanks of the Convoy
route, and to screen the assault area against enemy
channel based forces,

To escort each and every convoy,

To sweep sea mines out of all waters required for
NEPTUNE forces, and

To defeat enemy air attacks by an integrated program
of air cover and AA defense.

A. Plan for Minelaying

In order to assist in the protection of allied vessels
engaged in the assault, naval and air forces executed an
extensive minelaying operation (known as Operation MAPLE),
with the general purpose of impeding the movement of hostile
vessels against the invading forces. The objects of
Operation MAPLE were:

To impede the movement of light enemy vessels stationed
inside the Channel,

To impede ingress into the Channel by enemy naval forces
situated in the Atlantic and North Sea,

To compel enemy naval forces moving toward the NEPTUNE
area to follow a course to seaward of the extreme range
of enemy shore batteries and shore based fighter cover,
in order that allied surfaces forces would be free to
intercept their progress,

To disrupt enemy shipping generally during the critical
period, in order to reduce seaborne movement of enemy
reinforcements and supplies toward the battle area.

Minelaying was carried out by the following naval forces:

(a) HMS Apollo, (b) HMS Plover, (a) 10th, 50th, 51st and
52nd M.L. Flotillas, (d) 9th, 13th, 14th, 21st, 22nd and 64th
M.T.B. Flotillas. In addition, mines were laid from the air
by Halifax, Sterling and Lancaster bombers of numbers 1, 3, 4,
5 and 6 Groups, Bomber Command, R.A.F. Command of the Minelaying
operation was exercised by the normal authorities responsible
for minelaying in British home waters. The Naval
forces were accordingly under the direction of the Commanders-in-Chief,
The Nore, Portsmouth and Plymouth, and the Admiral
Commanding, Dover. Minelaying aircraft were under the direction

--412--

of the Air Officer Commanding-in-Chief, Bomber Command.
General control of all minelaying authorities was exercised
through the usual Admiralty Channels. Coordination
between the minelaying operation and the general NEPTUNE
naval plan was arranged by ANCXF, who stated his requirements
and coordinated the general plan. The MAPLE minelaying
plan was developed by ANCXF and is set out in his
naval plan Appendix XVII. Mines were laid with the object of:

Creating normal hazards to enemy shipping,

Endangering enemy light craft, and particularly E
and R-boats,

Presenting the enemy with a difficult minesweeping
problem.

The supply of mines was arranged by the Admiralty.

With the exception of the field laid in the Straits of
Dover, and an area mined by aircraft to the north of the
Frisian Islands, all the minefields were offensive in
character. The two semi-defensive minefields, referred to
above, were intended primarily to counter any movement of
enemy heavier forces from the east. Dormant preparations
were also made to reinforce these fields, and to lay mines
in the Kiel Canal or its approaches (Operation BRAVADO).

B. Minelaying Operations.

(17 April - 9 May) Routine offensive laying with
standard mines was continued, and, in
addition, special types of mines were introduced
into fields laid off Ijmuiden, the Hook,
the Scheldt, Boulogne, Fecamp, Le Havre, the
Brittany coast and the Frisian Islands. A proportion
of the mines laid were timed to become
effective at various dates so as to escape
being swept before the operation was due to begin.

--413--

Phase (3)

(9 May - 28 May). Operations continued as
in phase (2), with additional fields being
laid in the vicinity of Ushant, and on the
general line between the Gasquets and Ushant.
Minelaying with special mines, timed to become
effective at varying dates, was augmented in
the fields to the north of Le Havre and to the
north and northwest of Cherbourg. During this
phase, aircraft executed an extensive series of
minelaying operations in the Kattegat, Baltic
Heligoland Bight, Frisian Islands, and in the
Bay of Biscay, with the object of retarding the
movement of enemy vessels from these more distant
waters toward the Channel and assault area. On
the night of 12/13 May, a minelaying operation
was executed by Mosquito aircraft in the Kiel
Canal. Similar operations were executed on the
nights of 15/16 and 26/27 May, when mines were
laid by aircraft in the approaches to Aarhus,
Aalborg and The Sound, as a counter to possible
enemy movements from Norway. As these operations
involved some risk of compromise to the new types
of mines, it was not originally intended that they
should be laid from aircraft before 20 May. But to
enable full advantage to be taken of especially
suitable minelaying conditions, this date was anticipated
by five days in the minelaying in the Baltic.

Phase (4)

(29 May - 4 June). During this phase, operations
were primarily directed to the laying of special
mines off Ijmuiden, the Hook, the Scheldt, Calais,
Le Havre, Cherbourg, St. Malo, Morlaix, Brest, and
the Biscay ports. Aircraft also executed further
lays off Aalborg and in the approaches to Aarhus.

Phase (5)

(Nights of 5/6 June). Operations in Phases 1-4,
were, of necessity, related to a fixed date. Those
in Phase 5, on the other hand, were planned to be
carried out concurrently with the assault. The
original plan provided for the laying of mines:
(a) off Point de Barfleur, (b) southwest of Le Havre,
(c) off Etretat (in conjunction with Operation
TAXABLE), and (d) off St. Malo. In the event, only
the lay off Etretat was executed. In view of the
shipping congestion in the approaches to the assault

--414--

area and the resulting complication of the
projected lays, the other D-day minelaying
operations were abandoned.

Phase (6)

(6 June onwards). During this phase, the
majority of the Coastal Force minelayers were
diverted to escort and patrol duties. Further
limited operations off Le Havre were executed,
however, under the direction of NCETF. Aircraft
continued to lay mines off the Channel,
Biscay, the Channel Island ports, as a deterrent
to the use of these harbors by U-Boats.

During the course of Operation MAPLE, a total of 6,850
mines were laid. Of these, 42% were laid by naval forces
in 66 operations and 58% were laid by aircraft in 1800 sorties.1
These operations made an effective contribution to the general
immunity from surface and U-Boat attack enjoyed by the assault
forces. A considerable number of casualties were inflicted
on the enemy, and his minesweeping organization was stretched
to the limit. Minefields in the vicinity of Ushant and off
the Brittany coast had the desired effect of driving U-Boats
into open water, where they could be dealt with by allied
anti-submarine forces. The special operation in the Kiel
Canal resulted in a complete dislocation of the enemy organization
at an important moment. The entire operation cost
the allied cause, in casualties, only one Motor Torpedo Boat 2
and 19 minelaying aircraft.

--415--

Part IIINAVAL COVER FOR NEPTUNE

A. Countering the German Heavy Fleet.

The major distant naval threat was from the German
heavy fleet and associated units stationed in Norwegian
and Baltic Waters. In November 1943, these forces consisted
of two Battleships (one seriously damaged), two
Pocket Battleships, one unfinished Carrier, two Heavy
Cruisers, 4 Light Cruisers, from 16 to 25 Destroyers, and
miscellaneous lighter vessels.1
Between November and
invasion day, these forces were further reduced by constant
air and naval attacks.

The allied force charged with the responsibility of
guarding NEPTUNE from these forces, was the British Home
Fleet stationed at Scapa Flow and operating in the North
Sea and North Atlantic. Between 5 - 9 June 1944, the
Home Fleet in Scapa Flow consisted of three Battleships,
three Fleet Carriers, seven Heavy Cruisers, 12 Destroyers,
and numerous miscellaneous light forces.2
With it were
associated Number 18 Group Coastal Command (R.A.F.),
and various long distance heavy bombing formations of
Bomber Command.

This force was obviously adequate to deal with any
movement of the German heavy forces of the north. Indeed,
it had stood guard against them throughout the war. Little,
if any, coordination with ANCXF and SCAEF was required, and
control of the distant naval cover against this threat was

--416--

retained by Admiralty working through the normal command
channels of the Home Fleet. Throughout the critical
first days of the invasion, the German heavy forces in
the north failed to react, and the Home Fleet did not
even have the opportunity to repel an attempted "rush"
toward the channel area.1

B. Countering U-Boat Movements From the North.

Another threat from distant enemy naval forces was
that, when the invasion began, U-boats stationed in the
north might be transferred to the Channel. Admiralty
assigned CinC Western Approaches responsibility for guarding
against this threat.2
He (CinC Western Approaches) provided
a force consisting of three escort carriers3
with associated aircraft, and six groups of naval escort, stationed
some 130 miles westward of Lands End.4
This force, operating in conjunction with Coastal Command, maintained
a constant surveillance over the U-Boat transit area.
In the event, few contacts were obtained, and by 10 June,
four of the escort groups were transferred for use inside
the Channel.5

--417--

C. Sealing the Western Channel.

The task of sealing off the western channel approaches
from U-Boat or other penetration, was assigned to CinC
Plymouth, who was to operate under the general direction
of ANCXF.1
The strength of enemy forces based in the
Brittany and Biscay area, which were available to be sent
against NEPTUNE via the western approach, was estimated
to be five destroyers, five torpedo boats, 80 to 90 miscellaneous
light war vessels and 130 U-Boats. It was
thought that the enemy might be able to reinforce his U-Boats
to about 200.2

In order to prevent these forces from penetrating into
the Channel, where they could menace the flanks of the
convoy routes, CinC Plymouth organised a sea barrier, known
as the "CORK", in the western reaches of the channel.3
ANCXF allotted to CinC Plymouth the following forces with which to
seal the CORK: 12 fleet destroyers,4
four MTB flotillas,

The first step taken to seal the CORK was the laying
of extensive minefields along the west coast of Brittany
astride the enemy's coastal route. The object of this
mine barrier was to compel enemy U-Boats and other vessels
to detour sufficiently to seaward to be outside the range
of German fighter cover, in order to allow allied air and
naval forces an unmolested opportunity to attack them.1

On the night before D-Day, the general disposition of these forces was as follows:

One Destroyer Division carried out a constant patrol
in the Hurd Deep2
in order to arrest any possible
attempt by the enemy to rush a strong U-Boat pack
up the middle of the Channel;

A second destroyer patrol, known as the "Western Patrol",
was organized so as to operate with four destroyers in
an area about 50 miles north of Ushant.3
The object of this patrol was to intercept enemy vessels, and,
especially, destroyers proceeding from the Gironde toward NEPTUNE;

The U.S. destroyers and, at night, light coastal
forces of Plymouth command, were posted to seaward
of the exposed western arm of Force U's. convoy
route, and were supported by special air patrols;

This general plan for sealing the CORK, though
modified to fit special requirements, was continued throughout
NEPTUNE and afterward.2
Enemy destroyers in the Bay of Biscay did not begin to move against NEPTUNE until the
evening of June 6 (some 15 hours after the landings). They
were brought to action in the early hours of June 9, when
four of them departed Brest in the general direction
of the Channel. At 0120, they were intercepted 20 miles
northwest of the Ilde de Bas, by the 10th RN destroyer
Squadron, which sank one, drove another ashore, and damaged
a third. The latter, in company with the fourth, escaped
to Brest. This action virtually ended the threat to
NEPTUNE convoys from attack by enemy destroyers. On the
night of 4/5 July, destroyer patrols damaged three gun boats
in the vicinity of Morlaix. On the night of 12/13 June,
they carried out the diversionary operation ACCUMULATOR in
the Channel Island area.3
During the first two months of
NEPTUNE, constant attacks of opportunity were executed
against coastal transport.4

Anti-U-Boat operations in the CORK were conducted by
the combined Air-Navy patrol. The results obtained by
naval forces were not spectacular from the point of view
of "kills", but they were, none the less, highly successful
in that they achieved their principle object of stopping the
U-Boats from arriving in the convoy lanes. During the first
two months, no NEPTUNE losses were known to have been caused
by U-Boats.

--420--

D. Sealing the Straits of Dover

The task of sealing the eastern end of the Channel
was less difficult, as the Dover Straits are narrow and
do not exceed 20 miles breadth at some points. They
are well guarded, not only by numerous British coastal
batteries, but also by extensive stretches of unnavigable
shoal water. Moreover, German naval forces available to
penetrate the eastern barrier were not formidable. The
enemy disposed in the southern reaches of the North Sea,
southward of the barrier interposed by the Home Fleet, of
no more than 30 E-Boats, 65 R-Boats, 40 Minesweepers, and
some 45 miscellaneous small vessels. No U-Boats, Torpedo
Boats, Destroyers or heavier units were situated in these
waters.1
There was, however, a remote possibility that
some six Destroyers and ten Torpedo Boats from the Baltic
and the Bight might attempt to elude the patrols of the
Home Fleet.2

Under the general supervision of ANCXF, the Admiral
Commanding Dover was responsible for sealing the eastern
Channel.3
His first concern was to ensure that the allied
minefields, on the enemy's side of the Straits and elsewhere
astride enemy convoy routes, were strengthened and kept up
to full effectiveness.4
From the forces assigned him for his
various NEPTUNE tasks, he disposed ten squadrons of coastal
craft as a constant guard against miscellaneous vessels
which might try to penetrate into the Channel. He also
5

--421--

stationed his four destroyers, whose basic task was to
guard the east wall of the SPOUT and the eastern arm of
the Force L convoy route, in such a manner that they
could be quickly drawn into the Straits in case of an
unexpected sortie by German destroyers or torpedo boats.
In addition, strong air formations of Number 16 Group,
Coastal Command, operated to the requirements of A.C. Dover,
and maintained constant air surveillance over the entire
area of the Dover Straits.1

The enemy's reaction in the Dover area, however, was
limited to making preparations to arrest the expected
future assault against the Pas de Calais and the Low
Countries.2
No attempt was made to thrust naval forces
through the Straits of Dover.

E. Patrols Along the Convoy Flanks

A system of screening patrols was organised to protect
the channel convoy lanes from attack. Enemy naval
forces within the Channel consisted of one destroyer, four
torpedo boats, seventeen E-Boats, five R-Boats four
minesweepers, eighteen light gun craft, some thirty-seven
minesweeping trawlers, some thirty-four patrol vessels
and seventy-five harbor defense craft.3

Under the general direction of ANCXF, CinC Portsmouth
was responsible for operating the patrols on the western
flank of the SPOUT; the Admiral Commanding Dover, for those
on the Eastern flank.4
To man the patrols, ANCXF assigned
to CinC Portsmouth, four R.N. fleet destroyers,5
two frigates

--422--

and five flotillas of coastal forces, comprising 39
craft. He assigned to A.C. Dover, four R.N. fleet
destroyers1,
two frigates, and ten flotillas of Coastal forces, comprising fifty-four
craft.2
In addition to these naval forces, Number 19 and 16 Groups, Coastal
Command, R.A.F., operated to their general requirements.
Bombers carried out several devastating strikes against
enemy naval bases and ships in port.3

During the course of the war, an elaborate and efficient
chain of radar stations had been developed along
the entire southern coast of England. Those gave A.C.
Dover complete radar coverage of the Channel in his area,
while CinC Portsmouth had coverage more than half-way across
the Channel. To bring the southern edge of his area of
the Channel, which included the assault area, under radar
surveillance, CinC Portsmouth posted four frigates, mounting
powerful radar instruments somewhat to the south of mid-Channel.
Radar information was fed into central plots,
from all shore stations and from the radar frigates. Portsmouth
and Dover were thus able to maintain up to the minute
locations and movements of all objects in the Channel, and
to vector patrols against hostile vessels.4

The patrols were disposed as follows:

A seven mile gun zone was established on either side
of the SPOUT. Any ship found within this zone during
darkness was to be presumed hostile. Allied vessels
were to enter only in hot pursuit of the enemy;

--423--

The destroyers were to patrol along the outer edges
of the gun zone: these systems of patrols were
known as the East and West Walls of the SPOUT;

Dover's destroyers patrolled in single units along
a line from Dungeness to the east wall to seaward of the
coastal channel;1

Coastal forces, which were employed primarily during
the night or periods of reduced visibility, were
stationed, or carried out patrols as required.

--424--

PART IVASSAULT AREA: SCREEN AND ESCORTS

A. Allied Naval Dispositions.

ANCXF assigned to the appropriate Task Force Commander
the task of screening the assault area against
enemy naval penetration.1
Enemy naval forces within the
Channel consisted of an indeterminate number of human
torpedoes, self-exploding pilotless surface craft, sea
mines to be laid by aircraft, and the 195 miscellaneous
vessels in the preceding section.

To repel these enemy forces, the Task Force Commanders
established an area screen, detailing to it, a
proportion of the vessels allotted them by ANCXF. Manning
the area screen required a careful phasing in the use of
vessels. Until allied forces arrived in the assault area,
there was no screen. On arrival, a proportion of the
escorts and patrol vessels took up screening patrols.
Still later, other vessels, which had completed their
initial tasks of boat control, close fire support, or some
other job, took over patrol duties, while a proportion of
the escorts returned to the U.K. in company with the convoys.
In due course, most vessels capable of escort duty,
were transferred to CinC Portsmouth for escort duty to
facilitate his task of operating the post assault build-up
convoy program.2

--425--

B. Eastern Task Force.

Naval Commander Eastern Task Force delegated
control of naval forces screening his area to an authority
known as "Captain (Patrols)"1
During the assault phase,
this authority was stationed in the ETF flagship. Later
he exercised control from R.N. headquarters on the Far Shore.
In both cases, he was provided with full details of the
position and movement of all objects in the channel, from
the radar facilities of C in C Portsmouth, NCWTF and his own
ship and shore radar.

The system of defense employed in the eastern area was the following:

constant patrols to seaward by corvettes,
trawlers, and sometimes destroyers were
carried out;

every 24 hours one Division of four destroyers
was detailed as duty division for the entire
area while two other destroyers were
detailed as guard for areas G and J. By day,
these destroyers performed such other tasks
as were assigned, but they were subject to call
in case an attack threatened. By night they
were posted as directed by Captain (Patrols).
In neither case did they actively patrol up and
down the defense line. The plan was that
Captain Patrols would vector them against enemy
forces, whose presence was discovered by radar
or other means;

During the hours of darkness or low visibility,
this defense was augmented by a line of minesweepers
anchored 5 cables apart along a defense line
parallel to the shore and six miles to seaward;

This defense line was continued down the eastern
flank by a line called the TROUT line, composed
of LCG's and LCF's, anchored 1 cable apart. The
duty of the minesweepers and Landing Craft on
this defense line was to prevent all enemy ships
and craft from entering the British Assault Area,
to illuminate the outer areas when ordered and
to counter attack any submarine detected;

--426--

Two or three divisions of MTB's were stationed,
stopped but under way, to the North eastward of
the N.E. portion of the defense line;

Two or three sub-divisions of destroyers were
stationed on patrol, to the north of the western
half of the area, and sometimes to the northward
of the MTB's;

Other light forces were stationed close inside
the defense line, to act as reinforcements or as
"pouncers". B.Y.M.S. and M.M.S. were anchored
as minespotters, originally in the approach channels,
but later in the lateral swept channel established
within the area;

These defenses were augmented by a smoke screen
laid by specially fitted craft at dawn, dusk, and
as required.

The enemy's day activity was limited to one long
range torpedo attack, by torpedo boats from LE HAVRE, at
0450 on D-day. This attack caused the loss of the Norwegian
destroyer Svenner. The attack was assisted by the smoke
screen laid by Allied aircraft to cover the eastern flank
of the assault from batteries in the Le Havre and Villerville
areas. The enemy vessels, were however, engaged, and one
torpedo boat was hit by Warspite with 15-in salvoes and was
considered sunk.1

By night the enemy's attack was more determined.
On four occasions he operated torpedo boats, and on eight
occasions E and R-boats, in the eastern Task Force area. On
every occasion except one, these forces were intercepted and
forced to retire. In no case was any success obtained by
enemy. The line L.C.G. and L.C.F., anchored on the eastern
flank, took a heavy toll of the human torpedoes which attacked
in July. Two enemy torpedo boats were also damaged, five
E/R boats sunk, and E/R boat probably sunk, three E/R boats
badly damaged, four E/R boats damaged. E.T.F. casualties
were two boats damaged with three killed and ten wounded.

--427--

C. Western Task Force.

Naval Commander Western Task Force delegated command
and responsibility for the area screen to CTG 122.4. Commander
Area Screen (Captain Saunders in the U.S.S. Frankford). The
forces employed were:

The W.T.F. sector was sub-divided into areas
with code names (indicated on sketch); an
inner screen, about the anchorages, was formed
in Areas Oregon and Ohio by Force O, and in
areas Kansas and Vermont by Force U; as
required to defend their own forces from
landward attack by pilotless explosive motor
boats, human torpedoes, etc; or as required
for protection against attacks by U-boats which
might have pierced the outer area screen, or
as required for spotting air
laid mines.2

Initially the picket line, composed of
destroyers.3
P.C.s, and S.G.B.s, was formed
along the DIXIE Line (see sketch), and
connected at its eastern end with the outer
defense line of the Eastern Task Force. The
pickets were supported by destroyers, in pairs
or in company with P.T.s and M.T.B.s; along
the MASON Line there were counter-attack
divisions of P.T. boats. To avoid being
confused with enemy craft all P.T.s, M.T.B.s
and S.G.B.s remained in assigned stations at
low speed except when enemy contact developed.
They were continuously plotted by radar and
coached into position by designated destroyers.

--428--

[Page 429 skipped or missing...]

--429--

The first enemy attempts to enter the assault
area were made by E-boats or German coastal craft, during
the hours of darkness, by approaching close inshore down
the Cherbourg Peninsula. These craft were picked up on
radar by destroyers in the picket line at ranges of 10 to
12 thousand yards and taken under fire. The enemy always
approached at low speed, sometimes stopping when illuminated,
but always withdrew in the face of destroyer gunfire.
The screen was never penetrated but it is probable that the
enemy laid mines on these sorties.

On the night of D plus 3, enemy craft endeavoured
to pierce the Screen from approach positions north of the
DIXIE Line. These attempts were repulsed. Subsequently, in
order to cut off E-Boats which were passing near Pointe de
Barfleur, two attack units of S.G.B.s and P.T.s were
stationed in MOUNTAIN AREA and were vectored into positions
for counter attack by destroyer radar. Although these units
made no known kills of enemy E-Boats, their presence and
aggressive attitude are considered partly responsible for
the fact that no serious threat was made against the Screen.

Shortly after the assault, convoys and miscellaneous
ships often arrived at the assault area during darkness without
previous notice. It was difficult for pickets to
recognize these ships as friendly and in one instance, on
13 June, the British cable layer Murdaugh Monach was fired
upon by U.S.S. Plunkett. In addition to their screening
functions the pickets assisted in reporting mines laid by
aircraft, in extinguishing floating flares dropped by
aircraft, and in the warning they gave of impending air
attacks.

--430--

[Page 431 skipped or missing...]

--431--

D. Convoy Escort Forces

Every convoy was provided with a group of escorting
vessels to protect assault and build-up forces from enemy
air attacks and such enemy naval vessels as may have penetrated
through the layers of defense above described. The
principal problem was that of phasing the allocation of
escorts so that the ships involved could be used for other
tasks as well. Assault convoys were to be escorted mainly
by vessels, which would perform bombardment, area screening,
boat control and other duties, when they reached the
assault area. A few escort groups were "loaned" to the
assault forces by the C's in C, Home Commands. These,
together with bombarding ships which had spent their
ammunition, were used to escort early convoys returning
from the assault area. The "loaned" escort groups were
then "returned" to the Home Commands and applied to the
build-up escort program.

A proportion of the escort vessels, initially
assigned the assault forces for the assault phase were
later transferred to C in C Portsmouth for the Build-Up
phase.1
In addition to vessels engaged in escort work
during the assault, some 50 escort groups, with an average
of six vessels per group, were engaged in the escort of
build-up convoys. These escorts were of miscellaneous
types, including escort destroyers, corvettes, motor
launches and others. They were required to escort some
32 convoys and groups per day, which was the average number
at sea throughout the Build-up.2

During the assault, command of escorts were
exercised by the appropriate task force, assault force and
group commanders. During the Build-up it was exercised by
the Home Command through whose waters the convoy was passing.
Each escort group was assigned a base port, and authorities
responsible for north-bound sailings, assured, so far as
possible, that escorts were assigned to north-bound convoys
which were proceeding to their home ports. The convoys
suffered no losses from enemy action during the assault phase.

--432--

PART VNEPTUNE MINESWEEPING OPERATIONS

A. Plans For Sweeping German Minefields

The enemy's most dangerous available weapon,
for employment against Allied ships and seaborne forces,
was his sea mining. One of the major Allied naval tasks
was therefore to protect NEPTUNE forces from enemy minefields.
The naval plan was largely based upon the
requirement for sweeping Allied forces through the mine
barrier. Under the routing plan the Allied armada were
to sortie, from numerous ports along the south-west, south
and south-east ports of England, were then to converge on
Area Z, proceeding along the British Coastal Channel, and
were finally to turn southward, crossing the channel through
the SPOUT, in order to approach the assault area. The minesweeping
problem was to assure that those routes, the
assault area anchorages, and the manoevouring space were
free of enemy mines.

The enemy mine situation within these NEPTUNE
waters, was as follows:

Harbour entrances, (through which NEPTUNE
forces would sortie after their final assembly)
the British coastal channel, along which they
would pass to the converging area (Area Z), and
Area Z itself, were maintained in a mine-free
condition by normal mine sweeping searches
executed by Home Commands;

There was, however, the possibility that the
enemy, once he learned that the Allies were
assembling in mass, would lay mines from the
air in these waters;

To the southward of Area Z the waters were
unswept, but searches had indicated that no
enemy mines had been laid north of 50° N latitude;

The enemy was known to have laid a mine barrier
across the northern limits of the Bay of the
Seine;1

--433--

Southward of this barrier, the enemy
maintained a coastal shipping channel of his
own, which could be expected to be free of
enemy mines;

There was no evidence of mines, inshore of
the German coastal channel, but intelligence
was incomplete and there might be unknown
minefields;

There was no evidence of ground mines laid
in the shallow water along the beach, but
it was possible that there might be some, and
it was also probable that, after the assault
began, the enemy would lay more;

The enemy had available quantity of aircraft
with which he could lay mines after the assault
was under way.1

The general plan for dealing with mines, in
NEPTUNE waters, involved five steps:

The sortie and convoy routes, Area Z, and that
part of the SPOUT lying north of the German
mine barrier, were to be regularly searched up
until D-1 and after D plus 2, but not
immediately preceding the movement of the
assaulting forces.2

Ten channels, two for each assault force, were
to be cut through the mine barrier.

--434--

Transport areas, anchorages, and
manoevouring space for bombarding ships were
to be searched and swept;

The danger of ground mines in inshore waters
was to be disregarded during the assault,
but the areas were to be searched as soon as
sweepers were available;1
thereafter sweepers
were to stand by to sweep any ground mines
the enemy might lay after the assault started.

Channels were to be widened into one broad
passage as soon as possible.

In view of this plan, and of the disposition of
enemy mines, responsibIlity for all searching in and south
of the "barrier", and for sweeping force Us lateral passage
up to the barrier, was undertaken by the expeditionary forces.
Responsibility for searching and sweeping, in NEPTUNE sortie
and coastal channels, in Area Z and in the waters of the
SPOUT north of the barrier, was left in the hands of the
appropriate Cs in C Home Commands.2

B. Minesweeping Arrangements in the Assault Area

All minesweeping, in and south of the German mine
barrier was undertaken by the Naval Expeditionary Forces.
Responsibilities were divided as follows:

ANCXF retained direct control of the initial
ten approach channels through the mine barrier,
for searching and sweeping the transport areas,
and for subsequent widening the approach
channel, by sweeping out areas between the initial channels;

Task Force Commanders arranged for
searching or sweeping anchorages, inshore
mines, manoevouring space for bombarding
ships, and mines laid in the assault area
after the assault;

--435--

Each Task Force Commander delegated
command of minesweeping in his area to a
senior minesweeping officer who was responsible
for operation of all minesweepers
in each area, and for coordination with the
activities of the two Task Forces.1

The total strength of Allied minesweepers,
engaged in the assault,2
was 255 vessels. This force comprised:

Provision of such a large number of minesweepers
severely taxed Admiralty's resources. To meet the
requirement, minesweepers had to be withdrawn from other
important services. When the scale of the Assault was
increased from a three to a five-division basis, requiring
four additional channels to be cut for the two new
assault forces, it was necessary to allocate four additional
flotillas. One was a new flotilla, not commissioned until
the eve of the operation; one was an ancient flotilla
from the 1st World War; one was a decimated flotilla from
the Mediterranean; and one a Canadian flotilla which had
spent its entire career in escort duty.

C. The Passage and False Start

The passage was technically defined as starting,
when a vessel left the searched channels of the English
coast and as ending, when it entered the swept channels of
the mine barrier. The passage of all assault forces,
except certain convoys of Force U, was through the SPOUT.
The Assault Forces were not "swept" through this passage,2
as it was too short to enable minesweepers to precede the
Assault Forces and still enter the barrier on time, as
other minesweepers were not available for the job, and in
view of the fact that no mines were known to have been laid
in the area, as C in C Portsmouth had searched the SPOUT
at the last possible moment.

The route of Force U, from the West Country to the
entrance of approach channels 1 and 2, lay through an
unexplored area. Force U convoys sailed on 3rd June. Early
on the 4th, the 14th and 16th Minesweeping flotillas sent
sweeps to explore the route ahead of them. The 16th Minesweeping
flotilla received the postponement signal, at 0840 on the
4th June, and turned back. The 14th Flotilla, which was
further ahead, had not yet received the signal when they
found mines. The senior officer detached a PT boat to report
the minefield, but, the weather rapidly deteriorating,
extricated his flotilla and turned to the westward.

--437--

ANCXF considered that these mines were a chance lay,
jettisoned by E-boats, and decided not to attempt to change
the route of Force U. The following day, when the operation
was resumed, the 14th Minesweeping Flotilla swept and buoyed
a channel through the minefield, cutting one more mine. A
PT boat was detailed to shepherd the following convoys
through this channel. Further on, the 16th minesweeping
Flotilla cut four more mines along this route. Force U
passed safely through this minefield, but it claimed the
first casualty of the operation, U.S.S. Osprey.1

D. The Approach

The Approach was technically defined as beginning,
when the loading minesweepers of each Force began cutting
through the barrier, and as ending, so far as minesweepers
were concerned, when they had reached and swept the transport
area.2
Two channels were cut through the mine barrier for
each assault force in order to assure the safe approach of the
five Assault Forces. Each channel varied from 400 to 1200
yards in width. Each Assault Force was also provided with
one "transport area" of searched waters, 4 to 6 miles long
and some 2 miles wide, situated in the mine free German
coastal convoy channel.

Ten flotillas of fleet minesweepers were detailed
to cut the 10 channels and to search the five "transport
areas". Each flotilla consisted of nine fleet minesweepers,
to which was attached four minesweeping motor launches, two
Oropesa minesweeping "LL" trawlers, and four danlayers. The
motor launches, equipped with light sweeping gear, preceded
the leading fleet sweeps in order to clear a path for them.
The "LL" trawlers swept for magnetic mines while the danlayers
buoyed the channel, to guide the oncoming Assault Forces.

--438--

In order to assure that the channels cut would be
located in the proper positions, 10 - sonic underwater
buoys were laid in positions to mark the edge of the
enemy mine barrier in the Assault approach channels.1
These Buoys were laid so as to come alive on D minus 1, when
they would be utilized by H.D.M.L's, acting as marker
boats, to enable the mine sweepers to commence sweeping the
approach channels in the correct positions. Once sweeping
was begun from the correct starting points, accuracy of
navigation was aided by the use of QH and QM electronic
navigational devices and by taut wire. The course of all
the channels cuts were within 100 yards of their intended
positions.

To prevent the enemy from learning of the Allied
approach, or of the area at which the Assault was aimed,
until the last possible moment, it was essential that
barrier cutting minesweepers should not operate too far
in the van of the leading assault ships. The maximum speed
of the leading craft in some channels was 5 knots the minimum
safe minesweeping speed was 7½ knots. The minesweepers
were therefore required to lose approximately an hour and a
half. They accomplished this by back-tracking for 40
minutes just before they came within range of enemy radar.
Making two 180° turns with sweeps streamed was a difficult
manoeuver, further complicated by the tide. Before the
appearance of German beach obstacles, H-hour was scheduled
to be 3 to 4 hours before high water. On that basis the
cutting of the barrier would have begun, on a weak east-going,
and finished on a strong west-going, tidal stream.
This would have permitted the whole sweep to be carried out
in a "G" formation to starboard. The wasting of time could
have been accomplished by turning 180 degrees in succession,
back into the swept channels. But because of the beach
obstacles, H-hour was set at an hour or so after low tide.
The sweep, therefore, started with a strong east-going
stream, which, in the later stages, turned to a strong west-going
stream.

It therefore became necessary to begin the
operation in "G" formation to port and to change sweeps at
the change of the tide. A method of doing this, while wasting
time, was devised and adopted with minor variations by the
majority of flotillas. All ships, except the leader,
recovered sweeps in succession from the rear and formed
line ahead, protected by the leader's sweep. On completion,
ships successively turned 180 degrees, staring with the
rear ship, and retired along the channel already swept. After
all ships had turned, the leader recovered her sweep, turned

--439--

and followed the others. When sufficient time had been
lost, the flotilla turned 180 degrees together, streamed
starboard sweeps and, reaching the last danbuoy, formed
"G" formation to starboard. This was successfully tried
out in practice by some of the flotillas. Most of them
were unable to exercise the new manoeuvre, as they had been
employed during the last fortnight, in clearing minefields
laid by the enemy in his pre-invasion offensive, and in
searching prospective NEPTUNE convoy lanes.

This manoeuvre was successfully carried out by
all flotillas, even though the 9th and 18th had to execute
it in the middle of a minefield. The 6th flotilla was
unable to lose as much time as planned because the leading
landing craft in channel 5 were ahead of program. The
latter part of this flotilla's sweep, therefore, had to be
carried out at a speed of about 6 knots, but no mines were
found in this channel. The enemy were not alerted by the
approaching sweepers, although the 14th minesweeping flotilla,
which was operating the lateral convoy route of Force U, and
in the first approach channel, was in sight of the French
coast from the afternoon of D minus 1.1

During the passage and approach, the weather was
heavy. This caused little trouble to the fleet minesweepers,
but it made sweeping very difficult for the motor launches,
which were, however, able to carry out their task. ML's cut
two mines from the path of the leading fleet sweep of the
9th minesweeping flotilla. The danlayers also had trouble
with the weather. Some dan lights were smashed in launching,
but the reserve danlayers filled the gaps. All channels
were adequately marked and the Assault Forces found them
easy to follow. Sweep cutters were met in Channel 5, but
no mines were found. 29 mines were cut in Channels 2, 6 and
7. Throughout the approach, the leading minesweepers checked
their positions by QM, QH, and taut wire measuring gear. In
two cases one or the other method failed, but all flotillas
succeeded in laying their terminal dans within a cable of the
assigned positions and within a few minutes of the planned
time. The five transport areas were searched on schedule,
but no mines were found.

--440--

Immediately the sweeping of the approach channels
and transport areas was completed, the twelve flotillas
of fleet minesweepers turned to three other urgent tasks:

clearing lateral channels connecting the
inshore terminals of the ten approach channels; and

widening the approach channels.

These three tasks were executed concurrently. Three fleet
minesweeping flotillas were detailed to the Task force
Commanders for bombardment minesweeping, three for sweeping
connecting channels, and two to standby for special
requirements. The remaining four, operating under the
direct control of ANCXF, immediately began sweeping out the
areas in the German mine barrier lying between the approach
channels. They were joined by the other flotillas carrying
out this task, when the search of bombardment and lateral
areas was completed.

The intricate manoeuvres necessary to disengage
ten flotillas in a confined space were successfully
accomplished. In conducting the search of the bombarding
areas some flotillas operated within two miles of the enemy
shore. In this phase there was some mutual interference
between minesweepers. Some of the searches planned were
not completed before oncoming landing craft forced the
minesweepers out of the way. These searches, however,
revealed that the inshore areas were clear of moored mines.
The ten narrow channels through the German mine barrier were
inadequate to accommodate the requirements of the enormous
post-assault cross-channel shipping program. When the fleet
minesweepers had completed their assault task, they were
therefore employed in clearing the entire barrier between
the first and the last approach channels. In so doing, they
concentrated on merging two pairs of adjacent approach
channels to make them available by the end of D-day, and
their rejoinder with other minesweeping flotillas.

--441--

The clearance of the space between channels
3 and 4 (known as channel 34) and between 5 and 6 (channel
56) was completed according to plan on D-day; Channels 12
and 78 were completed on D plus 1; Channel 14 was finished
on a D plus 7; and channel 58 was cleared to a width of six
miles by D plus 8. The entire barrier within the SPOUT
was open by D plus 12. The clearance of the enemy mine barrier
was carried far enough to the north to ensure that the whole
of the minefields discovered during the approach was cleared.
78 moored mines were found in this field alone.

E. Sweeping Inshore Waters

Inshore waters, lying between the transport area
and the assault beaches, were not swept during the initial
assaults. The risk of loss from mines in these waters was
accepted because:

it was not thought that the Germans had laid
any mines in inshore waters;

the project would have demanded more sweepers
than were available;

the delay which would have been required
between the cutting of the barrier and the
assault was unacceptable; and,

minesweeping could offer little protection
in any case, in view of the period delay
mechanism with which enemy moored mines
were equipped.

Inshore areas, especially the boat lanes between
the transport areas and the beach, and the areas of the
artificial harbors were to be swept as soon after the
assault as possible. For this purpose, each assault force
was allocated one flotilla of YMS or BYMS, one flotilla of
British Motor Minesweepers, and a group of 6 minesweeping
LCT's. All three types of vessels were equipped with light
sweeping gear especially designed for sweeping moored ground
mines in shallow waters.1
Inshore waters were searched
shortly after the first assault. But no mines were found
until after the enemy began laying them from the air.

--442--

F. The Enemy's Minelaying Counterattack

It had been anticipated that the enemy, after
the assault, would counter attack strongly by laying
mines in the assault and Build-up channels. This
appreciation proved correct. In the first month after the
assault, the laying of ground mines by aircraft by night
was the enemy's chief weapon for impeding the Allied Build-up.
This mine-laying forced the Allies to take risks,
which had previously been considered unacceptable, inflicted
casualties, and slowed up shipping movements. The effect on
the Build-up was however negligible.

The first indication of the extent of the ground
mine problem came on D plus 1, when some 30 ground mines
were detonated in the neighbourhood of the CARDONNET shoal
in the UTAH area. It is uncertain whether this field was
in place before the assault, with period delay mechanisms
which prevented its discovery on D-day, or whether surface
craft succeeded in laying it on the night of D-day. The
field claimed seven casualties including two U.S. destroyers,
the Glennon and the Meredith, the U.S. Destroyer Escort Rich,
and the U.S. Fleet minesweeper Tide. In the eastern area
also the air mining effort mounted steadily. It soon became
apparent that the sweepers were not keeping pace with mines
dropped in the channels and anchorages. Fifteen casualties,
three vessels sunk and twelve damaged, were suffered in the
ETF area by D-plus 16, while some ninety mines had been
swept.

On 20 June it was discovered that the Germans had
been using a new and secret type of mine (the pressure mine),
which was unsweepable by existing Allied methods.1
To
counter this danger, a series of measures were taken which
were effective in reducing sharply in casualty rate, then
confined mainly to near misses on sweepers. The following
were the steps taken:

Airfields, from which enemy minelaying
aircraft were operated, where heavily and
repeatedly bombed;

--443--

Allied night fighter aircraft cover was
increased and special attention was given
to the intercepting of minelayers;

the width of ship channels was reduced,
while all available minesweepers were
concentrated on these narrower waters;

to reduce pressure caused by the movement
of ships, speed restrictions were imposed
on all vessels operating in mined waters;

when it was necessary to move heavy ships
in such shallow water that their speed could
not be reduced to a safe figure, tugs were
employed with a long tow, in order to avoid
pressure and acoustic actuations being applied
simultaneously;

when it was discovered that a swell would
reproduce the pressure conditions required
to fire an acoustic "oyster" mine and that
lower speed would then be no protection all
movements were stopped when such conditions
existed, until channels had been swept;

it was also learned that period delay
mechanisms could be worked off without
pressure actuation. Sweeping schedules
were accordingly adjusted, under swell
conditions to cover as large an area as
possible of all channels and anchorages.

G. Minesweeping at Cherbourg

The early capture and employment of a major port
on the Far Shore was essential to OVERLORD. Without it the
Allied armies could not be adequately supplied. The Germans,
fully realizing this fact, sought to prevent the Allies
from capturing Cherbourg and from putting it quickly in
workable condition. The German plan to make Cherbourg unworkable
included provision for sowing the approaches,
channels, anchorages, and berths, with a profusion of mines.

--444--

NCWTF put Commander M/S West in charge of the
operation of clearing mines from Cherbourg. Intelligence
data available, as to the extent of mining in and off the
harbor, was of great assistance in framing for this
difficult clearance.1
Before Cherbourg was taken, during
the northward advance of the U.S. Army along the Cotentin
Peninsula, channel "L" was extended along the east and
north coasts to protect bombarding ships employed in support
of the Army's advance. During these operations, the
minesweepers 2
repeatedly came under fire of shore batteries.
Within 24 hours of the silencing of the last battery, "H"
and "L" channels had both been established and an area off
the harbor entrance cleared to seaward of the 10-fathom
line. The clearance of moored mines, within the 10-fathom
line outside the harbor was effected by the two U.S. YMS
squadrons, the 167th BYMS, and 206th MMS Flotillas.

Inside the harbor, the principle adopted of first
clearing as much of the Grande Rade, as was necessary to
gain access to the Petite Rade, and enough of the latter to
provide a passage to the Avant Port de Commerce and to the
Nouvelle Plage. Each lap was first searched for snag lines
by LCV(P)s. A passage was then swept by ML's wide enough
to start Oropesa clearance with YMS. Ground minesweeping
of each lap was started, as soon as it was safe from moored
mines. Motor launches and LCV(P)s were used for clearing
very confined spaces in which not even a YMS could manoeuvre.

--445--

At the same time, two "P" parties of
Commodore Sullivan's port salvage organization, searched
Bassin Des Flots, the Avant Port de Commerce and the
shallows of the Nouvelle Plage, working outwards to meet
the sweepers. To avoid danger to "P" party divers from
exploding mines, these parties worked only for three hours
either side of low water. The mine-sweepers worked three
hours either side of high water. Entry to the landing
point, most easily reached, having been made as rapidly
as possible, clearance was extended to the docks and basins
which had been more thoroughly blocked. Cherbourg port was
free of mines and was receiving ships by 19 July.

H. The Score

Ships lost to enemy mines, and mines accounted
for between 4th June and 3rd July were:

A. Coordination of Coastal Command and Naval Operations

in conjunction with covering naval forces,
to impede the movement of enemy warships,
especially U-boats, from their northern
bases to the Biscay area;

in conjunction with naval covering forces,
to prevent enemy vessels, and especially
enemy U-boats, from penetrating into the
English channel;

to assist Allied naval forces in protecting
NEPTUNE shipping, convoys, and assault area,
from attack by enemy surface vessels and
U-boats operating within the channel;

to assist naval forces in disrupting enemy
sea-borne transport in order to impede the
movement of enemy reinforcements and supply
into the assault area and in order to make
German coastal supply lines difficult and
costly.

Operational command of coastal Air Forces, operating
in support of NEPTUNE, was exercised by the R.N.C.'s
Home Commands in conformity with the standard British system

--449--

for control of R.A.F. anti-U-boat forces.1
During the early stages of NEPTUNE planning, no special command
channels were established for coordinating the operations
of Coastal Command with NEPTUNE operations. ANCXF reported
his requirements to Admiralty or to the appropriate
Home Commands, and relied on them to make the necessary
arrangements. This method however proved to be clumsy,
especially in connection with tasks in close support of the
operation, and was found to be inadequate in providing the
required degree of integration. At a later date, Admiralty
authorized direct communication between Coastal Command and
the various commands of the Naval Expeditionary Force.
While this greatly facilitated the making of individual
and specific arrangements, no integrated NEPTUNE plan for
Coastal Command was developed and operations were executed
by more or less improvised methods.2

--450--

The forces engaged in these operations included
the U.K. based Aircraft and Coastal Command, six RN Fleet
Air Arm Squadrons, and U.S. Navy Fleet-Air-Wing Seven. To
provide continuous air patrols in the South Western
approaches, number 19 Group, which included the greater part
of RN and USN formations of anti-U-boat aircraft, was
disposed in the south and southwest under the orders of the
C's-in-C, Plymouth and Western Approaches. Some anti-shipping
aircraft were made available in this group, in
case the enemy attempted to send surface vessels from
the Bay of Biscay into the Channel. In the east and southeast,
Number 16 Group operated a formidable force of anti-shipping
aircraft. Arrangements were made to transfer anti-U-boat
squadrons from 19 Group to 16 Group of the enemy
sought to operate U-boats in the southern North Sea.
Number 18 Group was stationed in the north to counter
any movement from northern enemy ports into the Biscay or
channel area. A flexible system, of re-inforcing any of
these Coastal Command Groups from the resources of the
others, was devised to meet any developments which might
arise.

Coastal Command operations in support of NEPTUNE
opened in Norwegian waters on May 16. It had been anticipated
that the enemy might try to reinforce his Biscay
Flotillas by sending U-boats from the Baltic and Norwegian
ports to the Atlantic via the Northern Transit Area. This
appreciation proved correct, and to counter these movements,
Number 18 Group opened a vigorous and sustained offensive.
By the eve of the invasion, this offensive had resulted in
22 sightings, 13 attacks and 6 kills. By 30 June the score
was 44 sightings, 28 attacks and 13 probable kills.

By the 6th of June, the majority of the enemy's
U-boats were assembled in the Biscay area,1
as part of his
basic strategic plan, assigning the U-boat a major role in
the plan to frustrate the invasion. Their task was to
enter the channel and, by getting between the assaulting
forces and their British Bases, to prevent the Build-Up.
When the Normandy landings began, the U-boats made for the
assault area, proceeding on the surface whenever possible
in a order to attain the utmost speed.

--451--

Coastal Commands main task was to prevent these
U-boats from arriving inside the channel. It planned an
air barrier over CORK the entire area of the western approaches
to the channel, extending from the shores of Devon and Cornwall
to the shores of Brittany, and from the Scilly Isles to
the Cherbourg Peninsula. This area was covered with air
patrols, which were so timed that every spot in CORK came
under observation every thirty minutes.1
As CORK was so wide
that U-boats could not pass through it without surfacing, and
as the entire surface was under constant surveillance, few,
if any, submarines were able to enter the channel undetected.
The solid wall of air patrols in the CORK proved effective.
On the night of 6/7 June, 11 U-boats were sighted and 6
attacked; in the following 24 hours, 10 more were sighted,
6 attacked, and 3 probably sunk. After thirty days, the
score for the operations in the Biscay and Channel areas
was 96 U-boats sighted, 59 attacked, 6 certainly sunk, and
a great many more probably or possibly sunk.

After this initial set back, the U-boats began
to try to get through by remaining submerged and by relying
on "SCHNORKEL" to ventilate and charge. 2
These tactics
effectively restricted their speed and freedom of manoeuvre
and had a most distressing effect on their crews. The few
U-boats, which did succeed in penetrating the air barrier,
arrived in an exhausted condition. During the first two
months no losses to the invasion forces were known to have
been caused by U-boats.

--452--

While the U-boats were being dealt with in the
south-west and the north-west, Coastal Command also
cooperated with the Navy in actions against enemy surface
forces. It was expected that German destroyers and light
craft would operate vigorously against Allied convoys.
Hence, 16 and 19 groups were strengthened to assist naval
forces in warding off this threat. Soon after the invasion
began, the enemy tried to reinforce his surface craft in the
assault areas by bringing up destroyers from the Gironde.
On the 6th of June some of these vessels were attacked by
aircraft south of Brest, but the damage inflicted did not
prevent the enemy from making port. Two days later, four
destroyers tried to round the Brest Peninsula, but were
brought to action by the Royal Navy. One destroyer was
sunk, one driven ashore and a third was forced back to
Brest in a damaged condition. The beached destroyer was
later attacked by aircraft and reduced to a total loss.
After this, the enemy made no further attempts to reinforce
his surface craft from the west.

In the early stages of the invasion, the enemy
operated channel based light forces, mainly E-boats, on
a considerable scale against the assault area. Some 30
of these vessels were based between Boulogne and Cherbourg,
but the number was substantially reduced by surface action,
including coastal aircraft, and by several heavy bombing
attacks against Le Havre and Boulogne. The operations of
Coastal Command against these light forces consisted
mainly of continuous anti-shipping patrols in the Channel.
A great many air attacks, mostly at night, were made in
conjunction with naval patrols against E-boats, R-boats,
minesweepers, and trawlers. In addition, aircraft carried
out considerable reconnaissance work, dropping flares and
directing naval forces to their targets.

Coastal Command also contributed to the successful
Allied effort to disrupt the enemy's coastwise transport.
On 15 June, north of Schiermonnikoog, a merchantman of
8,000 tons and a naval auxiliary of 4,000 tons were sunk
and three minesweepers of the escort damaged. On 29 June
a 1,000 ton tanker and one of its escorting minesweepers
was attacked and damaged; on 20 June two "M" class minesweepers,
one armed trawler, and an auxiliary were badly
hit off Concarneau. Apart from the losses suffered, the
enemy was obliged to divert, to purely defensive tasks,
numbers of minesweepers and naval escort craft urgently
required elsewhere.

--453--

Bomber missions also contributed to the protection
of seaborne NEPTUNE forces from enemy naval action.1
The employment of bombers in mine-laying has been described
already.2
On the evening of 14 June, 353 heavy bombers
attacked Le Havre with 1026 tons of bombs, including
twenty-two 6-tonners, destroying, among other things, over
25 enemy naval vessels. On the 15th June, 297 heavy
bombers attacked Boulogne, concentrating on U-boat pens.3

B. Air Defense by Combined Allied Air Forces

The defense of NEPTUNE from enemy air attack was
a major task. Some 1,515 enemy aircraft were available for
use against NEPTUNE, including 340 heavy bombers, 75
reconnaissance bombers, 75 fighter-bombers, 560 twin-engine
fighters, 390 single-engine fighters, and 75 coastal aircraft.
These planes were so disposed that some 185 aircraft were in
the Normandy area, 360 in the Pas de Calais area, 135 in
Holland, 375 in north-western Germany, and 100 in
Scandinavia. The Germans were not considered to be able to
deploy more than this against NEPTUNE, as their remaining
air resources were required on their eastern and southern
fronts.

--454--

Allied air forces, available for defense against
hostile aircraft, consisted of the 9th U.S. Air Force, and
the British Second Tactical Air Force. Taken together
these comprised some 2,300 aircraft.1
Allied fighter
cover was employed in the following manner:-

Five squadrons of sixteen planes each
maintained a constant patrol over the convoy
lanes, with five additional squadrons on
call if required.

Ten squadrons, of sixteen planes each ,
maintained a constant patrol over the
assault beaches, with a reserve of ten
squadrons on call at all times.

Some eight squadrons of light and medium
bombers were available as required to
bomb the enemy airfields from which attacks
were launched.

Until air fields could be constructed on the
Far Shore, the problem of maintaining fighter patrols over
beaches and convoy lanes taxed the endurance of fighter
craft. The distance to and from airfields in England was so
great, that each plane was able to patrol for only 20 minutes
over the beaches. A large proportion of the air cover effort
was thus absorbed in simply going and coming.

The command and control of NEPTUNE air forces was
not delegated to the lower echelons of command, as was the
policy with Army and Naval forces. It remained, on the
contrary, in the hands of the very highest echelon, AEAF.
The air operation was in fact one continuous battle and not
a series of local engagements. In order to keep all Allied
air defense resources available to meet any enemy threat,
air forces could not be tied down to a series of local tasks,
but had to be free to move about over the entire area, as the
enemy reaction required.

The single authority, exercising control over all
NEPTUNE fighter defense aircraft, the "Advanced Headquarters
AEAF", was located at Uxbridge, near London. This "Advanced
Headquarters" was kept informed of the movements of enemy
aircraft in the entire Western European area, by reconnaissance,
radar, and other resources. All such information was
fed into Uxbridge and air deployments were made accordingly.

--455--

The fields from which the aircraft operated were
scattered all over southern England. This system of
remote control was obviously unable to direct effectively
local movements of aircraft in the assault area. This was
assured from three fighter direction tenders. These were
naval landing ships (LST's) equipped with all the radio
and radar gear required for the tactical control of aircraft.
An elaborate operations room was installed in which
the movements of all aircraft, friendly or hostile was
plotted. Intelligence of the local situation was provided
by local radar and reconnaissance. Intelligence of more
distant air movements was supplied by radio from Uxbridge.
The navy operated the vessels, while airforce commands operated
the fighter control.

Under this system of local control, planes on patrol,
and also reserve planes sent specially as reinforcements, were
despatched by the control authority at Uxbridge. On arrival
each plane made radio contact with the air operation room of
the fighter direction tender. While the plane remained in the
area, the FDT vectored it to its target, and generally directed
its movements. When its tour was completed, usually
because its gasoline was exhausted, control of the plane was
returned to Uxbridge. Three FDT were employed for the
operation, one stationed in the WTF area, one in the ETF area,
and one in mid-channel. Fighter Direction Operation rooms,
complete with radar and radio equipment were installed on
three other ships, which were stand-bys in case the FDT's
were sunk.

The Air Force Command intended to transfer local
control of fighter aircraft from the FDT's to the French
Shore on D plus 1. To do so they landed several Ground
Control Intercept (GCI) parties on D-day. These were,
however, badly mauled in landing and were unable to function
until after D plus 6. In order to enable individual ships
to call for help against hostile aircraft, and to provide
for relaying information of movements of hostile aircraft,
a special radio channel was provided. Calls for help were
received at Uxbridge and on the FDT's, one or the other of
which took appropriate action. The Joint Force Broadcast
a general purpose radio circuit, to which nearly every
vessel was tuned, was used for air warnings, to keep ships
and craft warned of movements of hostile and friendly planes.

--456--

The anti-aircraft armament of all vessels was
available for use against hostile aircraft, while each
Commanding Officer was responsible for using it for the
protection of his own ship. The main problem, however,
was that of keeping ships from shooting down friendly
aircraft, and of coordinating the use of anti-aircraft
guns with movements of air covering forces. In order to
drive enemy planes by anti-aircraft fire up to an altitude
where the Allied fighters could deal with them, and then
to stop AA fire, so that these friendly planes could do
their job, a plan was tried which provided that ships
should fire their AA only on a signal, and should cease
fire on a signal. This plan however, did not work, as
the gunners on many ships did not obey the signals. At
a later date, the plan was tried again in captured ports
with some success.

The enemy's air reaction to NEPTUNE was unexpectedly
small. Most of his fighters were used in a defensive
role against Allied bombers. The first sortie against
NEPTUNE shipping came at about 3 o'clock on D-day, some
fifteen hours after the first arrival in the assault area.
During the following night some eight-five aircraft, mostly
mine layers, flew over the beaches and shipping lanes. On
D plus 1, some fifty-nine enemy aircraft were in the battle
area of which fifteen were destroyed. Thereafter the enemy's
reaction dwindled gradually. By the middle of July, air
attacks on the NEPTUNE area had virtually ceased.

Footnotes:

p.410 #1
For numbers, formation and organization of these vessels, see
ON 1, Appendix II, III, IV and ANCXF Report, Para. 2. For details
of numbers of convoys, see ON 7, Appendix 1, ON 16, Section
B, and ON 9. This great number of convoys lasted for
only a few days just before and just after the assaults. During
the Build-Up, however, the extraordinary average of 32 Convoys
and smaller groups was maintained. See ANCXF Report, Para. 64.

p.410 #2
The routing and movement of the assault forces is discussed in
detail in Chapter VI, Section 3. The SPOUT was the name given
to the system of cross channel convoy lanes. Its northern end,
which was about 10 miles wide, was located about 15 miles south
of NAB Tower (near Portsmouth) and marked by the "Z" buoy. Its
southern end, which was about 30 miles wide, debauched into the
assault area at 49°40' north latitude. Convoys hugged the coast
line until they reached the northern end of the SPOUT; they then
turned south and crossed the channel in various lanes within the
SPOUT.

p.410 #3
This was the estimate of enemy naval strength as of 1 Nov 1943,
made by the U.S. Chiefs of Staff in CCS 300/3 of 18 Nov.43. The
estimates for destroyers and below were only approximations.

p.410 #4
This was the estimate for February 1944, given in XFNP Page 3.

p.416 #2
The balance of the Home Fleet was on duty in the Channel
in immediate support of OVERLORD. The ships at or working
out of SCAPA were:
2nd Battle Squadron: Duke of York,Anson,Howe.Fleet Carriers: Furious,Indomitable,Victorious.Cruisers: (1) 1st C.S. - Kent,Berwick,Devonshire,
(2) 10th C.S. - Bermuda,Jamaica,Sheffield.3rd Destroyer Flotilla: Milne,Marne,Matchless,Meteor,Musketeer,Wager,Wakeful,Wessex,Whelp,Wizard,Volace,
and Nubian.

p.417 #1
The quiescence of the German fleet in the north may be explained
in part by any or all of the following: (1) Fuel
shortage. On 5 June 1944, the allocation of fuel to the
German Navy was cut 33%. Fuel issued to submarines was not
cut so that the heavier units absorbed a proportionately
larger share of the cut. (2) The battleships were damaged
and the cruisers were being used primarily for training.
(3) The German High Command expected the main allied landing
later and in the Low Countries and gave their orders accordingly.
(See Admiralty NID 24/2 65/45, p.45, p.42-43.

p.417 #2
No direct channel of command between ANCXF and SCAEF and CinC
Western Approaches was required or provided, in order to
achieve the necessary coordination of effort for this task.

p.418 #1
See Chapter III for a detailed account of the command
relations between the Channel Home C's in C, ANCXF and
Admiralty.

p.418 #2
See ON I Para. 10; ON I, Appendix VII Annex K; CinC Plymouth
NEPTUNE Report, Section 2, Para. 21. There are striking
discrepancies in the figures shown in the above sources,
especially on the question of U-Boats. CinC Plymouth reckoned
that there were no more than 40 odd immediately available on
D-day. The balance, perhaps, may be accounted for by the fact
that some were on other operations, some never got down from
the north, and that a ratio of 60% was the maximum available
at any time for sea duty.

p.418 #3
The CORK was bounded on the east by the eastern limit of the
Plymouth Command (a line running from Portland Bill, to Cap de
le Hague). It was bounded on the north and south by the coasts
of Brittany and Cornwall and on the west by a somewhat intermediate
line at about 7°00' west longitude.

p.419 #1
For details of the minelaying program, See Section 2,
Chapter VII.

p.419 #2
The Hurd Deep is located in mid-channel, directly south of
Devon. The patrol operated between 50° 12' North, 2° 21'
West, and 49° 56' North, 3° 16' West.

p.419 #3
Since the main enemy destroyer force was still in the Gironde
on the night before D-day, this patrol was not manned until
the night of 6 June (night following D-day) when air reconnaissance
showed that enemy destroyers were moving northward.

p.420 #1
For details of those air operations, see Chapter VII,
Section 8.

p.420 #2
One exception to this, was that the U.S. destroyers were
withdrawn after the assault phase. See ON I, Appendix
II, Section B.

p.421 #2
See ON I, Para.11. Should those forces be so employed,
the enemy heavy forces would have no screen in case they put to
sea. It was, therefore, considered unlikely that they would
be sent to hazard the dangers of the Home Fleet Patrols and
to try to penetrate the Channel barrier.

p.422 #4
To put this arrangement into effect, the boundary between
the Portsmouth and Dover commands was altered on 28 May 1944
for operational purposes from the line Dungeness-Dieppe to
a line from Worthing (which is located some 20 miles east of
Portsmouth to a position 50°00'N, 0° 15'W, thence to 49° 40'N
0° 00' W, thence due east to the French Coast.

p.423 #2
For ANCXF's assignment of these vessels, see ON 5, Appendix
II, Section A and B. It will be recalled that a part of
Dover forces were to enable him to establish the eastern
Channel barrier as well as to man the Channel patrols.

p.423 #3
See Chapter VII, Sections 8 and 9 for details on air patrols.

p.423 #4
The Channel in CinC Plymouth area was so wide that he had
to rely on air reconnaissance to direct his ships into the
vicinity of enemy vessels.

p.424 #1
This was in order to cover the SPOUT, the coastal channel
and, at the same time, to be able to cover the Straits.

p.425 #1
See ON 9, Para. 21, 27, 28 and 29. It will be recalled
that ANCXF held naval command over the entire Channel area
during the assault. Within the assault area, which was
all the water south of 49° 40' N. latitude lying between the
Cherbourg Peninsula and Cap Antifer, he exercised command
through the Task Force Commanders. In all the rest of the
channel, he exercised command through the C's inC, Home
Commands, whom he directed to function generally in accordance
with their normal procedure. This accounts for the fact that
the Home Commands operated the patrols screening the convoy
routes, while the Task Force Commanders operated the patrols
screening the assault area.

p.425 #2
Details of the manner in which ANCXF arranged for the necessary
transference of vessels after the assault while leaving the
Task Force Commanders a free hand in continuing the area screen
for their own area will be found in ON 9 and more especially
on ON I, Appendix 11, sections A and B.

p.426 #1
The elaborate orders which NCETF promulgated for the defense
of the British Assault Area, are contained in his British
Assault Area Defense Orders (short title BAADO) dated
30 April 1944 and numbered ETF 859/4. The resume given
here is very broad.

p.427 #1
According to the account of the German Naval CinC West,
Admiral Krancke, the attack was carried out by the 5th
German Torpedo Boat Flotilla, 15 torpedoes in all being
fired. Only minor damage was sustained by the Torpedo
boats; but the 15th Patrol Flotilla, stationed off Le
Havre "ran into heavy enemy fire" under which one vessel
sank, after striking a mine.

p.428 #1
Destroyers were employed in screening and bombarding
duties in rotation.

p.428 #3
Guard destroyers were assigned as convenient from reserve
fire support destroyers of the assault forces.

p.432 #1
For allocations of escorts see ON 1 Appendix II, Section A
and B, ON 13 Appendix III. For instructions to Task and
Assault Force Commanders as to transferring escorts to
post assault duties see ON 9, Para.16.

p.433 #1
This barrier was thought to extend northward from latitude
50° N to a line, running 092° and 328° from a position 49°27'
.5 N and 0° 54' W. See ON 6 para. 5.)

p.434 #1
The exact number was uncertain because the enemy could
easily employ craft for this purpose which were normally
bombers.

p.434 #2
ON 6, Para.16. During the assault phase all available
sweepers would be engaged with the mine barrier or
inside the assault area. The risk was not great as the
British coastal channel was normally constantly searched,
the area north of the barrier was not believed to have
mines in it, and it was searched during the weeks before
NEPTUNE just to make sure.

p.435 #1
Because (a) there was insufficient sweepers to search them,
(b) no mines were thought to exist in these waters anyway,
and (c) in any case, ground minesweeping ahead of forces
could not give security in view of the period delay
mechanism with which the mines mere equipped.

p.440 #1
As will be seen in Chapter VIII, Section 8, this flotilla
was screened from radar detection by Allied Radar
counter measures.

p.441 #1
In order to safeguard the bombarding battleships,
cruisers, destroyers, and other ships which would be
required to move around in the congested assault area,
often very close to the shore, it was considered
essential that their movements should be preceded by
minesweeping. Bombardment was to begin before H-hour
so that no time could be wasted between the completion
of sweeping the approach channels and transport areas
and the beginning of sweeping for bombardment forces.
The areas which were swept are defined in ON 6, Appx.I.
For diagrams see ANCXF Report Vol I,Appx.l4 and ANCXF
Report Vol.III,Annex H.

p.442 #1
See ANCXF Report,Vol.III,p.63. It was originally planned
to use also LCV(P)s equipped with very light gear for work
very close to shore, but in trials it was found that the
gear broke up before the craft could reach the shallow water.

p.443 #1
This was a pressure acoustic mine which depended for
actuation on both the increased water pressure caused
by a ship passing in its immediate vicinity and the
sound of the ship. Another variation was the pressure
magnetic mine.

p.445 #1
Two rows of G.Y. mines with snag lines and 8 ft. of 5/8th
inch chain moorings had been laid across the eastern
entrance of the GRANDE RADE. The western entrance was
similarly blocked with mines with delayed release
sinkers. The GRANDE and PETITE RADES shoreward of the
two fathom lines were well fouled with "Katies". There
was a line of G.Y. mines across the entrance to the
PETITE RADE and both RADES had been well sprinkled with
acoustic, magnetic, moored and apparently delayed release
moored mines.

p.450 #1
This system was broadly as follows: (a) Coastal Command,
whose primary mission was anti-U-boat warfare,
was one of the major sub-divisions of the R.A.F.,
(some other major sub-divisions were Bomber
Command, Training Command, Fighter Command, etc.)
and was commanded by the Air Chief Marshal,
Commander in Chief Coastal Command. For
administrative and logistic purposes he was
directly under the command of British Chief
of Air Staff, but the Chief of Air Staff
had assigned operational control of Coastal
Command Forces to Admiralty.
(b) The major operational sub-divisions of
Coastal Command were GROUPS. Admiralty
assigned operational control of groups based
in the United Kingdom to appropriate Home
Commands.
(c) The C's in C, Home Command, employing
a suitable air staff from Coastal Command,
and in conjunction with naval forces, then
operated assigned groups for air patrol of the
waters for which they were responsible.
(d) Supervision and coordination of joint
operations was effected by the joint control
of Admiralty and C in C Coastal Command. (See
Fairwing 7, History, for further details.)

p.451 #1
On that date they (the U-boats) were offensively deployed.
This fact is another striking indication of the fact that
the enemy had been unable to discover the approximate
invasion date.

p.452 #1
The reason the thirty minute interval was chosen was
because a U-boat was believed to use up, in a crash dive
approximately as much battery energy as could be charged
into the batteries in thirty minutes surface charging.

p.452 #2
The "SCHNORKEL" was a pipe with two vents which was
pushed up from the submarine's interior. This enabled
a U-boat, at periscope depth, to expel exhaust gases from
its diesel motors and suck in fresh air from above the surface.
Submarines employing Schnorkel were hard to detect
because the exposed portions were only some 20 inches in
diameter and extended only some 6 feet above the water.
During the early months of the invasion the enemy had not
fully learned how to use it, but later in the summer when
they were able to use it at greater depth and with less
exposure above the surface, the entire character of the
anti-U-boat effort was changed.

p.454 #1
Questions relating to the integration of Naval and
Bomber operations are dealt with in Chapter VIII which
deals generally with Bombardment and Air Bombing in
their role of defense against enemy shore action and
offensive assistance to the army.

p.454 #3
These were berths for U-boats covered over by reinforced
concrete.

p.455 #1
This figure does not include Allied Bomber Forces, nor does
it include fighters employed in the support of Bombers.
Bombers, however, contributed effectively to the defense
of NEPTUNE against enemy hostile aircraft by executing
several attacks on enemy airfields from which hostile aircraft
were flown.