Military history of the Philippines during World War II

The Commonwealth of the Philippines was attacked by the Empire of Japan on December 8, 1941 nine hours after the attack on Pearl Harbor (the Philippines is on the Asian side of the international date line). The United States of America controlled the Philippines at the time and possessed important military bases there. The combined American-Filipino army was defeated in the Battle of Corregidor in April 1942, but guerrilla resistance against the Japanese continued throughout the war. Uncaptured Filipino army units, a communist insurgency and supporting American agents all played a role in the resistance. Due to the huge number of islands, the Japanese never occupied many of the smaller and more minor islands. Japanese control over the countryside and smaller towns was often tenuous at best.

In 1944, Allied forces liberated the islands from Japanese control in a naval invasion.

In September 1940, Germany, Italy, and Japan had allied under the Tripartite Pact. The United States banned the shipment of aviation gasoline to Japan in July 1940, and by 1941 shipments of scrap iron, steel, gasoline and other materials had practically ceased. Meanwhile, American economic support to China began to increase.

Japan and the USSR signed a neutrality pact in April 1941 and Japan increased pressure on the French and Dutch colonies in Southeast Asia to cooperate in economic matters. Japanese forces occupied the naval and air bases of southern Indochina on 22 July 1941. The Philippines was almost completely surrounded.

General George C. Marshall, US Army Chief of Staff, stated, "Adequate reinforcements for the Philippines, at this time, would have left the United States in a position of great peril, should there be a break in the defense of Great Britain."

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