Japanese activity Objectives The Japanese planned to occupy the Philippines as part of their plan for a "Greater East Asia War" in which their
Southern Expeditionary Army Group seized sources of raw materials in
Malaya and the
Netherlands East Indies while the
Combined Fleet neutralized the
United States Pacific Fleet. Five years earlier, in 1936, Captain Ishikawa Shingo, a hard-liner in the
Imperial Japanese Navy, had toured the Philippines and other parts of the Southeast Asia, noting that these countries had raw materials Japan needed for its armed forces. This helped further increase their aspiration for colonizing the Philippines. The Southern Expeditionary Army was created on 6 November 1941, commanded by General
Hisaichi Terauchi, who had previously been minister of war. It was ordered to prepare for war in the event that negotiations with the United States did not succeed in peacefully meeting Japanese objectives. They also included the condition of America's acceptance of their position in the Pacific as a superior force, with the testament of their occupation of China, but they did not get what they wanted. Under Terauchi's command were four corps-equivalent armies, comprising ten divisions and three combined arms brigades, including the
Japanese Fourteenth Area Army. Operations against the Philippines and Malaya were to be conducted simultaneously when Imperial General Headquarters ordered. The invasion of the Philippines had four objectives: • To prevent the use of the Philippines as an advance base of operations by American forces • To acquire staging areas and supply bases to enhance operations against the Dutch East Indies and
Guam • To secure the lines of communication between occupied areas in the south and the
Japanese Home Islands • To limit the Allied intervention when they attempt to launch an offensive campaign in Australia and the
Solomon Islands via dispatching all the forces stationed in the country and other neighboring nations
Invasion forces Terauchi assigned the Philippines invasion to the 14th Army, under the command of Lieutenant General
Masaharu Homma. Air support of ground operations was provided by the 5th Air Group, under Lieutenant General
Hideyoshi Obata, and the
United States Army's
Philippine Department. General
Douglas MacArthur was recalled from retirement by the
War Department and named commander of USAFFE on 26 July 1941. MacArthur had retired in 1937 after two years as military advisor to the Philippine Commonwealth and accepted control of the Philippine Army, tasked by the Filipino government with reforming an army made up primarily of reservists lacking equipment, training and organization. On 31 July 1941, the Philippine Department had 22,532 troops assigned, approximately half of them Filipino. MacArthur recommended the reassignment of department commander Major General
George Grunert in October 1941 and took command himself. The main component of the department was the U.S. Army
Philippine Division, a 10,500-man formation that consisted mostly of
Philippine Scouts (PS) combat units. The Philippine Department had been reinforced between August and November 1941 by 8,500 troops of the
U.S. Army Air Forces, and by three
Army National Guard units, including its only armor, two
battalions of
M3 light tanks. After reinforcement, the department's strength was 31,095, including 11,988 Philippine Scouts. MacArthur organized USAFFE into four tactical commands. The
North Luzon Force, under Maj. Gen.
Jonathan M. Wainwright, defended the most likely sites for amphibious attacks and the central plains of
Luzon. Wainwright's forces included the PA
11th,
21st and
31st Infantry Divisions, the U.S.
26th Cavalry Regiment (PS), a battalion of the
45th Infantry (PS), and the 1st Provisional Artillery Group of two batteries of 155 mm guns and one
mountain gun. The Philippine
71st Infantry Division served as a reserve and could be committed only on the authority of MacArthur. The
South Luzon Force, under Brigadier General
George M. Parker Jr., controlled a zone east and south of
Manila. Parker had the PA
41st and
51st Infantry Divisions and the 2nd Provisional Artillery Group of two batteries of the
86th Field Artillery Regiment (PS). The
Visayan–Mindanao Force under Brigadier General
William F. Sharp comprised the PA
61st,
81st, and
101st Infantry Divisions, reinforced after the start of the war by the newly inducted 73rd and 93rd Infantry Regiments. The 61st Division was located on
Panay, the 81st on
Cebu and
Negros, and the 101st on
Mindanao. In January a fourth division, the
102nd, was created on Mindanao from the field artillery regiments of the 61st and 81st Divisions acting as infantry (they had no artillery pieces), and the 103rd Infantry of the 101st Division. The 2nd Infantry of the Philippine Army's 1st Regular Division and the 2nd Battalion of the
U.S. 43rd Infantry (Philippine Scouts) were also made a part of the Mindanao Force. USAFFE's
Reserve Force, under MacArthur's direct control, was composed of the Philippine Division, the
91st Division (PA), and headquarters units from the PA and Philippine Department, positioned just north of Manila. The 192nd and 194th Tank Battalions formed the separate Provisional Tank Group, also under MacArthur's direct command, at
Clark Field/
Fort Stotsenburg, where they were positioned as a mobile defense against any attempt by airborne units to seize the field. Four U.S.
Coast Artillery Corps regiments guarded the entrance to
Manila Bay, including
Corregidor Island. Across a narrow strait of water from Bataan on Corregidor was
Fort Mills, defended by batteries of the 59th and 60th Coast Artillery Regiments (the latter an anti-aircraft unit), and the 91st and 92nd Coast Artillery Regiments (Philippine Scouts) of the
Harbor Defenses of Manila and Subic Bays. The 59th CA acted as a supervisory unit for the batteries of all units positioned on
Forts Hughes,
Drum,
Frank, and
Wint. The majority of the forts had been built circa 1910–1915 and, except for Fort Drum and Battery Monja on Corregidor, were unprotected against air and high-angle artillery attack except by camouflage. The USAFFE's aviation arm was the
Far East Air Force (FEAF) of the U.S. Army Air Forces, commanded by Major General
Lewis H. Brereton. Previously the Philippine Department Air Force and Air Force USAFFE, the air force was the largest USAAF combat air organization outside the United States. Its primary combat power consisted of 91 serviceable
P-40 Warhawk fighters and 34
B-17 Flying Fortress bombers. Tactically the FEAF was part of the Reserve Force, so that it fell under MacArthur's direct command. As of 30 November 1941 the strength of U.S. Army troops in the Philippines, including Philippine units, was 31,095, consisting of 2,504 officers and 28,591 enlisted (16,643 Americans and 11,957 Philippine Scouts).
Mobilization MacArthur's mobilization plans called for induction of the ten reserve divisions between 1 September and 15 December 1941. The timetable was met on 1 September with the induction of one regiment per division but slowed as a lack of facilities and equipment hampered training. The second regiments of the divisions were not called up until 1 November, and the third regiments were not organized until after hostilities began. Training was also seriously inhibited by language difficulties between the American cadres and the Filipino troops, and by the many differing dialects (estimated at 70) of the numerous ethnic groups comprising the army. By the outbreak of war, only two-thirds of the army had been mobilized, but additions to the force continued with the induction of the Constabulary and a portion of the regular army, until a force of approximately 130,000 men was reached. The most crucial equipment shortfalls were in rifles and divisional light artillery. MacArthur requested 84,500
M1 Garand rifles to replace the World War I
M1917 Enfields equipping the PA, of which there were adequate numbers, but the War Department denied the request because of production difficulties. The divisions had only 20% of their artillery requirements, and while plans had been approved to significantly reduce this gap, the arrangements came too late to be implemented before war isolated the Philippines. By contrast, the Philippine Division was adequately manned, equipped, and trained. MacArthur received immediate approval to modernize it by reorganizing it as a mobile "triangular" division. Increasing the authorized size of the Philippine Scouts was not politically viable (because of resentments within the less-well-paid Philippine Army), so MacArthur's plan also provided for freeing up Philippine Scouts to round out other units. The transfer of the American
34th Infantry from the
8th Infantry Division in the United States to the Philippine Division, accompanied by two field artillery battalions to create a pair of complete
regimental combat teams, was actually underway when war broke out. The deployment ended with the troops still in the United States, where they were sent to defend Hawaii instead.
Other defense forces The
United States Asiatic Fleet and
16th Naval District, based at Manila, provided the naval defenses for the Philippines. Commanded by Admiral
Thomas C. Hart, the surface combatants of the Asiatic Fleet were the heavy cruiser , the light cruiser , and thirteen
World War I-era destroyers. Its primary striking power lay in the 23 modern submarines assigned to the Asiatic Fleet. Submarine Squadron (SUBRON) Two consisted of 6 s, and SUBRON Five of 11
Porpoise and s. In September 1941, naval patrol forces in the Philippines were augmented by the arrival of the six
PT boats of
Motor Torpedo Boat Squadron Three. Likewise, the China
Yangtze Patrol gunboats also became part of the Philippine naval defenses: , , , , and . In December 1941, the naval forces were augmented by the schooner . The U.S.
4th Marine Regiment, stationed in
Shanghai since the late 1920s, had anticipated a withdrawal from China during the summer of 1941. As personnel were routinely transferred back to the United States or separated from the service, the regimental commander, Colonel
Samuel L. Howard, arranged unofficially for all replacements to be placed in the 1st Special Defense Battalion, based at
Cavite. When the 4th Marines arrived in the Philippines on 30 November 1941, it incorporated the Marines at Cavite and
Olongapo Naval Stations into its understrength ranks. An initial plan to divide the 4th into two regiments, mixing each with a battalion of Philippine Constabulary, was discarded after Howard showed reluctance, and the 4th was stationed on Corregidor to augment the defenses there, with details detached to Bataan to protect USAFFE headquarters. Additionally the
United States Coast and Geodetic Survey, a paramilitary survey force, operated in Manila with the ship
USC&GSS Research. ==Attack on Clark Field==