WW2-era fort in the Philippines
Fort Mills (Corregidor, the Philippines) was the location of US Major General George F. Moore's headquarters for the Philippine Department's Harbor Defenses of Manila and Subic Bays in early World War II, and was the largest seacoast fort in the Philippines. Most of this Coast Artillery Corps fort was built 1904–1910 by the United States Army Corps of Engineers as part of the Taft program of seacoast defense. The fort was named for Brigadier General Samuel Meyers Mills Jr., Chief of Artillery 1905–1906. It was the primary location of the Battle of Corregidor in the Japanese invasion of the Philippines in 1941–42, and of the recapture of Corregidor in February 1945, both in World War II.
Overview.
The United States acquired the Philippines as a territory as a result of the Spanish–American War in 1898. The Taft board of 1905 recommended extensive, then-modern fortifications at the entrance to Manila Bay. The islands there had been declared military reservations on 11 April 1902. Construction soon started and the forts were substantially complete by 1915 as the Coast Defenses of Manila and Subic Bays (renamed Harbor Defenses in 1925). All of them were on islands at the mouth of the bay, except Fort Wint on Grande Island in Subic Bay. As the only large island of these, Corregidor had more gun batteries than the others, along with barracks, other garrison buildings, and facilities for controlling two underwater minefields. Corregidor also had 13 miles of electric railway, an unusual feature in US forts. The forts were designed for one purpose: to prevent enemy surface vessels from entering Manila Bay or Subic Bay. They were designed before airplanes became important in war, and (except for Fort Drum) were vulnerable to air and high-angle artillery attack, being protected only by camouflage. Except for the mortar batteries, the turrets of Fort Drum, and the two guns of the 1920s Batteries Smith and Hearn, the forts' guns had restricted arcs of fire of about 170°, and could only bear on targets entering the bay from the west.
Construction.
The initial construction on Fort Mills was largely complete by 1911 except three 3-inch gun batteries. The initial gun batteries were:
Three additional batteries of two guns each followed within a few years; Battery Keyes in 1913 and Batteries Cushing and Hanna in 1919. The 3-inch "mine defense" guns were intended to prevent enemy minesweepers from clearing paths through underwater minefields.
The last new armament at Fort Mills until 1940 was significant but small in quantity: Batteries Smith and Hearn, completed in 1921. These had one M1895 gun each on an M1917 long-range carriage, with an elevation of 35° and 360° of traverse, with range increased from on a disappearing carriage to . The disadvantage was that the guns were completely unprotected. This type of battery was also built at eight other harbor defense commands in CONUS, Hawaii, and Panama. In 1923 the Washington Naval Treaty prohibited additional fortifications in the Pacific, thus the Philippine forts received no further weapons until after 1936, when Japan withdrew from the treaty, rendering it void. Ironically, had these batteries been modernized, they would have been casemated, restricting them to a 180° field of fire, and would have been less useful against the Japanese on Bataan. One result of the Washington Naval Treaty was the diversion of twelve 240 mm howitzers on a ship bound for the Philippines to Hawaii, where they were placed on fixed mountings on Oahu. The total lack of mobile high-angle artillery was a major impediment to the defense of the Philippines.
Spare gun barrels were provided near some batteries, including Smith and Hearn, due to the inability to re-line used barrels except at specialized facilities in the continental United States (CONUS).
Battery names.
The name sources for the batteries at Fort Mills were:
Minefields.
Manila Bay and Subic Bay had Army-operated minefields as well as naval mines. These minefields were designed to stop all vessels except submarines and shallow-draft surface craft. In Manila Bay, two controlled minefields were placed, one extending west from Corregidor to La Monja Island, and the other extending north from Corregidor to the Bataan Peninsula east of Mariveles Bay. Both of these were operated from Corregidor. Also, in mid-1941 US Navy minefields of contact mines were laid between Mariveles Bay and La Monja Island, and between Corregidor and Carabao Islands, to close off the bay approaches not covered by Army mines.
On the night of 16–17 December 1941 the passenger ship SS "Corregidor" (formerly HMS "Engadine") hit a mine and sank near Corregidor Island. The ship departed Manila that night without obtaining permission from the US Navy's Inshore Patrol, which meant the minefield operators were not alerted that a friendly ship was departing the harbor. The minefield's usual state in wartime was active, which meant they would detonate on contact. This probably applied to the mines in the designated ship channel as well. When the ship was spotted, some accounts state that Colonel Paul Bunker, commander of the Seaward Defenses, ordered that the minefield remain active. Due to wartime conditions, no official investigation was ever conducted, leaving many questions open. The location at which the ship sank has not been determined, for example. Accounts state that US Army officers informally told Filipino reporters that the mines were placed in safe mode immediately after the sinking. The ship was crowded with 1,200 to 1,500 persons, mostly Filipino civilians evacuating to Mindanao. 150 Philippine Army personnel and seven Americans were on board, along with several 2.95-inch mountain guns badly needed by the forces in the southern Philippines. Three PT boats ("PT-32", "PT-34" and "PT-35") picked up 282 survivors, of which seven later died.
The Malinta Tunnel.
The main part of the Malinta Tunnel complex was built on Corregidor from 1932 to 1934, with construction continuing until the Philippines were invaded in December 1941. Most US forts of this era had only small underground facilities, and this tunnel complex was the largest in the US coastal defense system. Due to the Washington Naval Treaty's prohibition on new fortifications, most of the complex was built without appropriated funds, using Filipino convict labor for unskilled tasks, and explosives slated for disposal. During the siege, the Malinta Tunnel proved important to the survival of the Philippine government, the military high command, the medical staff, and numerous civilians.
Japanese conquest of the Philippines.
Prelude.
From the late 1930s through the surrender in 1942 a number of batteries for GPF guns were built at Fort Mills. These were mobile field guns adopted by the Coast Artillery Corps for use in "tractor-drawn" units, such as the 92nd Coast Artillery. At least a few of these were delivered to the Philippines in 1921 with transfer of the 59th Coast Artillery to the islands. Nine batteries with emplacements for 22 guns were built. The US Army's official history states that 19 of these weapons were on Corregidor during the final battle in 1942. Most of these batteries simply had "Panama mounts", circular concrete platforms to stabilize the gun on its mobile carriage. One battery was exceptional, Battery Monja in the southwest part of Corregidor, with two emplacements. One or both of these were casemated by being built into a rock face; this proved to be crucial to the battery remaining in action during the siege. By December 1941 there were seven antiaircraft batteries totaling 28 3-inch guns on Corregidor (including one nearby on Bataan), some manned by the 60th Coast Artillery (AA) and some manned by batteries of the harbor defense regiments.
On 26 July 1941 Lieutenant General Douglas MacArthur was recalled to active duty and made the commander of U.S. Army Forces in the Far East (USAFFE), which included the Philippine Scouts and the Philippine Commonwealth Army. MacArthur had been an official U.S. advisor to the Philippine forces as a Philippine Field Marshal from 1935 to 1937, and had continued this function as a civilian since his retirement from the U.S. Army at the end of that period.
The siege begins.
The Japanese invaded northern Luzon a few days after the attack on Pearl Harbor on 7 December 1941 that brought the US into the war. They advanced rapidly, with other landings elsewhere, notably at Legazpi in southeast Luzon on 12 December, Davao on Mindanao on 20 December, and Lingayen Gulf on 22 December. On 26 December 1941 Manila was declared an open city, with the Philippine government and MacArthur's headquarters evacuated to the Malinta Tunnel. Amid the evacuations, a re-inauguration ceremony for Philippine President Manuel Quezon's second term was held just outside the tunnel on 30 December. The Japanese entered Manila on 2 January 1942. Five days later the U.S. and Philippine forces completed a fighting withdrawal to the Bataan peninsula, northwest of Corregidor, and prepared to defend it. In the northern Philippines, this left only Bataan, Corregidor, and Forts Hughes, Frank, and Drum in Allied hands. This situation had been anticipated in the prewar War Plan Orange-3, under which the forces in the Philippines were expected to hold out at the mouth of Manila Bay for six months. By that time it was anticipated that a relief expedition from the U.S. might arrive. General MacArthur had hoped to defend the Philippines more aggressively under the Rainbow Plan, and was able to get some reinforcements in the months prior to the U.S. entering the war, but this fell apart with the rapid Japanese advance in December 1941. And, with almost all of the Pacific Fleet's battleships sunk or damaged at Pearl Harbor, and the Japanese advancing in several parts of Southeast Asia at a much greater rate than expected, no relief was organized. Although extensive guerrilla operations were conducted by Filipinos with U.S. support, U.S. forces did not return to the Philippines in strength until the invasion of Leyte Gulf in October 1944.
One aspect of MacArthur's Rainbow Plan was the Inland Seas Project, intended to defend a shipping route to keep his forces supplied. Part of this was a buildup of Philippine Commonwealth forces, and a projected deployment of coast artillery weapons manned by them in the central Philippines. In 1940-41 eight railway guns and 24 GPF guns were delivered to the Philippines, without crews as they were to be locally manned. The 8-inch guns were sent north in December 1941 to engage the invading Japanese forces, but six of them were destroyed by air attack. One gun was eventually placed on a fixed mount as Battery RJ-43 on Corregidor in March 1942; the other may have been at Bagac, Bataan. Reportedly the Corregidor gun fired only five proof rounds, then went unused for lack of a crew until knocked off its mount by bombing or shelling. The history of the Bataan gun is unknown. Most or all of the 24 155 mm GPF guns were eventually deployed at Corregidor and/or Bataan.
Fall of Bataan.
Although the US and Filipino forces achieved success in defending Bataan through the end of February, they had taken 50 percent casualties and were worn out and poorly supplied. Also, the British fortress of Singapore had surrendered on 15 February, and the Japanese had taken several major islands of the Dutch East Indies, essentially preventing any reinforcement of the Philippines. Philippine President Manuel Quezon, with his family and senior officials, was evacuated to the southern Philippines by the submarine on 20 February. MacArthur was ordered by President Franklin D. Roosevelt to relocate to Australia to prevent his capture and to direct further operations. He departed Corregidor on 12 March 1942, initially by PT boat to Mindanao, completing his journey by air. On 20 March he made a speech with the famous phrase "I shall return". He left Lieutenant General Jonathan M. Wainwright IV in a subordinate command in the Philippines, telling the key officers there that he (MacArthur) would control the Philippines from Australia. However, he neglected to inform Washington of this arrangement, and Washington intended Wainwright to be in charge. It was not until 20 March that the extent of Wainwright's authority and degree of independence from MacArthur was clarified by a message from General George C. Marshall, the Army chief of staff.
The Japanese in Bataan received substantial reinforcements and replacements in March, including 240 mm howitzers and aircraft, and prepared for an offensive scheduled for 3 April. It started with a five-hour air and artillery bombardment that destroyed many of the Allied defensive