Luftwaffe service.
The first Dornier Kampfgeschwader.
In late 1936, the Do 17 E-1 began to be mass-produced. The first "Luftwaffe" units to receive the bomber were "Kampfgeschwader 153" ("KG 153"), and "KG 155". "Aufklärungsgruppe " (F)/122, a reconnaissance unit, began converting to the Do 17 F-1. In early 1937, KG 255 was formed, also to be equipped with the Do 17 E-1.
According to the "Generalquartiermeister der Luftwaffe", 479 Do 17s were on strength. Some 100 more had been lost in crashes or sent to Spain. On 12 March 1938, Do 17Es of "KG 155" dropped pro-Nazi leaflets on Vienna, as a prelude to the city's occupation during the German "Anschluss" operation. KG 153 received its first Do 17 E-1s on 20 September 1938 as part of a mass re-equipment program (note the significance of the date). The unit was redesignated KG 3 on 1 May 1939. "KG 155" converted on to the type in early 1938. KG 252 was also equipped with the Do 17M, at this time to meet the threat of the Sudeten Crisis. By December 1938, it had 26 Do 17s and 17 crews. On 1 May 1939, the "Kampfgeschwader" was redesignated "Kampfgeschwader 2".
Spanish Civil War.
The Do 17's baptism of fire came during the Spanish Civil War (1936–39), where it outpaced most enemy fighters and performed well. The Spanish nicknamed the Dornier the "Bacalao" ("Codfish"). In early 1937, mass production began on the Do 17E and Do 17F series. The Do 17 F-1 was to replace the Heinkel He 70 as a high-flying fast reconnaissance aircraft, while the Do 17 E-1 was to supplant the "Legion Condor"'s aging Heinkel He 111B bomber. However, more modern Soviet-supplied Republican aircraft were capable of intercepting the E and F variants, which prompted an upgrade of the Dornier's defensive armament.
Among the units committed to Franco's cause was "Hauptmann" Rudolf Freiherr Von Moreau's 4.K/88. On 6 January 1937, it was decided by Erhard Milch, Albert Kesselring
and Ernst Udet that the Legion should have more modern aircraft. Soon 12 Do 17 E-1s, as well as He 111B-1s and Ju 86D-1s were dispatched to serve in Spain. The unit was named VB/88 ("Versuchsbomben Staffel", meaning Experimental Bomber Squadron). VB/88s Dorniers were involved in a strike around Guernica, but that particular unit's objective was a bridge, rather than civilian areas. VB/88 dropped 8 tonnes (9 tons) of bombs, while K/88 added 37 tonnes (41 tons) over the city itself causing the deaths of about 1,500 people. The bombing of VB/88 straddled the bridge. The only other target hit by the German bombers that day was the rail station. On 8 July 1937, the Dorniers flew multiple sorties to protect Nationalist forces now threatening the capital, Madrid. At this point, the Junkers Ju 86s had been withdrawn and replaced by the Do 17Fs. In the spring of 1938, another unit, 1.A/88, equipped with Do 17s, also arrived in Spain. A total of 27 Do 17E, F and P variants were part of the "Condor Legion".
Polish Campaign.
A series of new models introduced the new enlarged nose, greatly increasing defensive firepower, finally settling on the Z models, which were widely available by 1939. During the first phase of World War II, the Do 17, along with the He 111, formed the backbone of the "Luftwaffe"'s "Kampfgruppen". From 1939 to 1940, four of the "Luftwaffe"'s bomber groups, KG 2, KG 3, KG 76 and KG 77 operated the Dornier. KG 76 and KG 77 operated the first generation Do 17E, with the other two "Kampfgeschwader" operating only the Do 17Z on the outbreak of war. On 1 September 1939, 533 Dorniers and 705 Heinkels were combat-ready. The total strength of the Dornier force was approximately 100 Do 17 E-1s, 32 M-1s, 188 Z-1 and Z-2s as well as 213 P-1s. Its reliability and robustness made it highly popular in the "Luftwaffe".
During the campaign, Do 17s of I./KG 2 took part in the Battle of Bzura, in which they used incendiary bombs against Polish forces consisting of Army Poznań and Army Pomorze. These raids caused a huge number of Polish casualties, who by now had retreated to dense wooded areas, contributing to their vulnerability. The Do 17 had performed well and could use its speed to outrun Polish fighter aircraft under some circumstances.
Norwegian Campaign.
The only Do 17 unit known to have taken part in the Norwegian Campaign was the 1.(F)/120 ("Aufklärungsgruppe") long-range reconnaissance unit. It operated from Lübeck Blankensee, in northern Germany until the occupation of Denmark, and was then based at Stavanger on 10 April 1940, after the "Wehrmacht" had secured southern Norway. Equipped with the Do 17 P-1, it provided reconnaissance intelligence over the Norwegian coast and the North Sea.
Western Europe.
The first German aircraft shot down over France during the war was a Dornier Do 17P of 2(F)123, brought down by Pilot Officer Mould's Hawker Hurricane of No. 1 Squadron RAF on 30 October 1939. The Dornier, Wrk Nr. 4414, constructed at Blohm &amp; Voss, crashed near Vassincourt, killing all three of its crew, "Hauptmann" Balduin von Norman, "Oberleutnant" Hermann Heisterberg and "Feldwebel" Friedrich Pfeuffer.
On 10 May the Dornier units, "Kampfgeschwader 2", "KG 3" and "KG 4", were under the command of "Fliegerkorps. II". "Kampfgeschwader 76" and "77" also operated the Do 17 under "Fliegerkorps I" and "Fliegerkorps VIII". The Do 17 saw its usefulness diminish during the French campaign owing to its limited bomb load and range. The design continued to be favoured by the "Luftwaffe" aircrews, as it was more maneuverable than the He 111 or Ju 88, and because of its ability to perform low-level strikes well. An example of this was a raid carried out by KG 2 against the RAF-controlled airfield at Vraux on 10 May. Six Bristol Blenheims and two Fairey Battles of No. 114 Squadron RAF were destroyed, with many more damaged. However, Allied fighter resistance on the first day was severe, and KG 2 and KG 3 of "Fliegerkorps II" lost a total of nineteen Do 17s between them on 10 May. Only two weeks into the campaign, KG 2 and 3 suffered fuel shortages, keeping the Dorniers grounded and forcing some attacks to be aborted. By the beginning of June, the Dornier "Geschwader" were encountering less opposition and losses declined sharply, as the "Armée de l'Air" was no longer a sufficient threat. However, over Dunkirk, the RAF fighters inflicted a high loss rate. On 2 June, thirty German aircraft were destroyed, including sixteen Do 17s (four from KG 2 and twelve from KG 3). The Dornier units dropped some 320 tonnes (350 tons) of bombs.
Battle of Britain.
During the Polish campaign, the Do 17Z could use its 427 km/h (265 mph) maximum speed to stay away from most enemy fighters, and its light armament was effective. It also fought with success during the Battle of France and losses were relatively light, although when facing modern fighters like the Hawker Hurricane, the bomber proved slow in comparison and more vulnerable. When it faced British fighters during the Battle of Britain, it was shown that fast, well-armed monoplane fighters had changed the balance between bomber and fighter decidedly in favour of the latter. The Do 17 suffered in early raids.
Since the Fafnir was a low-altitude engine, the "Luftwaffe" responded by employing the Do 17 units in a number of terrain-following mass raids in an attempt to evade fighter opposition. The Dornier was manoeuvrable in comparison to the Heinkel and the more robust nature of radial engines made it ideal for low-level attacks, with a number of units being fitted with 20 mm cannon. An example of one of these raids was the attack on RAF Kenley on 18 August, 1940, when nine aircraft from 9th Staffel of KG 76 led by Haupt. Joachim Roth, flew at very low altitude to avoid being detected by British radar and followed part of the London to Brighton railway to find their target. Four aircraft were destroyed in the attack and the remaining five were all damaged. At least one aircraft was lost to rocket propelled parachute and cable devices. Another was damaged by exploding bombs, due to the low altitude at which it was flying. The Junkers Ju 88 was now entering service in larger numbers, replacing the Do 17 at higher altitudes. The Dornier excelled at low-level attacks. However, this was becoming more and more dangerous. The British were now firing rocket-powered parachutes into the path of low-flying aircraft and dragging them from the skies. Losses were considerable.
The Dornier's performance advantage at low altitude became moot on 7 September 1940, when the "Luftwaffe" switched to the bombing of London (known as the Blitz), requiring all-out attacks at medium altitude. Losses mounted and on 15 September 1940, the three Dornier-equipped "Kampfgruppen" suffered heavily, losing 20 shot down and 13 damaged.
A significant event took place on 15 September 1940, now known as "Battle of Britain Day". Among these was the famous casualty of Dornier Do 17 Z-2 Wk Nr.2361, bearing the "Geschwaderkennung" code of F1+FH, 1."Staffel"/KG 76 flown by Robert Zehbe. Zehbe developed engine trouble and lagged half a mile behind the main bomber stream. His Dornier attracted a swarm of fighters. Eventually Ray Holmes of 504 Squadron, out of bullets, rammed the bomber. The tail came off and air pressure snapped off the outer wings short of the engines. The bomber crashed onto the forecourt of London Victoria station. Zehbe bailed out, only to die later of wounds suffered during the attack, while the injured Holmes bailed out of his plane and survived. This event became one of the defining moments of the Battle of Britain and elicited a congratulatory note to the RAF from Queen Wilhelmina of the Netherlands who had witnessed the event. In the same action Dornier Do 17 F1+FS of 8."Staffel"/KG 76, flown by Rudolf Heitsch, was found in a field near Shoreham. The Dornier was found to be fitted with a flamethrower, installed in the tail. Oil, nitrogen, and hydrogen cylinders were found in the fuselage, while the external pipe was fitted with a jet. Initially, it was concluded that it was a smoke producing device to feign damage. But it was discovered that it was a device that was triggered by one of the rear gunners to destroy a fighter pursuing the bomber from line astern. However, the lack of oxygen meant that the device failed to function, and only a continual spray of oil was emitted.
The losses for the Do 17 in August and September were considerable. In August 1940, 54 Dorniers were lost and another 20 written off due to technical problems and accidents. In September 50 more were lost, with 31 Do 17s and crews missing in action. In October another 36 Dorniers were lost. Dorniers had improvised armament of eight machine guns installed to increase defensive firepower, but still were unable to counter fighter attacks.
The battle continued into October as the "Luftwaffe" concentrated on night attacks which were carried out by units mainly equipped with the Heinkel He 111 and Junkers Ju 88, as they had bigger bomb loads, and the Ju 88 had a greater speed.
The Dornier Do 17's losses in the Battle of Britain are given as between 132 and 171, the lowest losses as a ratio of the three German bomber types.
With the introduction of the Junkers Ju 88 and the new Dornier Do 217 entering production, the Do 17's days were numbered, and production ceased in mid-1940. Even with the end of production, the Dornier saw action in notable numbers after the Battle of Britain, in the Balkan Campaign, Operation Barbarossa (the invasion of the Soviet Union), and with the other Axis air forces.
Balkans Campaign.
Initially, Yugoslavia had been pro-German, and looked set to join the Axis Powers, but a military coup toppled the government and declared itself neutral. Infuriated, Adolf Hitler ordered the conquest of Yugoslavia. The Yugoslavs had ordered twenty Do 17 Ka-2s at the end of 1940. These machines differed from the German Dorniers in that they were powered by French Gnome-Rhône Mistral Major engines, and had non-German weapons and instruments. In 1940, the Yugoslavs license-built fifty of these variants, but most were destroyed in the campaign.
The "Luftwaffe" committed "Luftflotte 4" to the invasion. Included in its strength were KG 2 and KG 3, the only "Kampfgruppe" in a force of seven equipped with the Do 17. Among