The Filipino resistance to Japanese occupation was one of the largest guerrilla movements of the war. What began as scattered bands of soldiers who refused to surrender after the fall of Bataan and Corregidor grew into a sophisticated network of over 260,000 armed fighters operating across the archipelago.
Guerrilla organizations varied from highly disciplined military units to loosely organized civilian resistance groups. They established radio networks that provided intelligence to MacArthur's headquarters in Australia, maintained shadow governments in Japanese-controlled territories, operated coast-watching stations, and conducted ambushes, sabotage, and raids.
By 1944, the guerrillas controlled significant portions of the Philippine countryside, confining Japanese forces largely to cities and major installations. When MacArthur returned in October 1944, guerrilla units provided critical intelligence on Japanese dispositions and supported the landings with diversionary attacks. Many guerrilla leaders had maintained contact with American submarine missions that supplied weapons and radio equipment throughout the occupation. The resistance came at a terrible cost: Japanese reprisals against civilians were brutal, including the Manila Massacre of 1945.