Philippine resistance against Japan

During the Japanese occupation in World War II, there was an extensive Philippine resistance movement, which opposed the Japanese with active underground and guerrilla activity that increased over the years. Fighting the guerrillas were a Japanese-formed Bureau of Constabulary (later taking the name of the old Philippine Constabulary during the Second Republic), Kempeitai, and the Makapili. Postwar studies revealed that around 260,000 persons were organized under guerrilla groups and that members of anti-Japanese underground organizations were more numerous. Such was their effectiveness that by the end of World War II, Japan controlled only twelve of the forty-eight provinces.

Also by the end of the war, some 277 separate guerrilla units made up of some 260,715 individuals fought in the resistance movement. Select units of the resistance would go on to be reorganized and equipped as units of the Philippine Army and Constabulary.

Background
The Attack on Pearl Harbor (called Hawaii Operation or Operation AI by the Japanese Imperial General Headquarters (Operation Z in planning) and the Battle of Pearl Harbor ) was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941 (December 8 in Japan and the Philippines). The attack was intended as a preventive action in order to keep the U.S. Pacific Fleet from interfering with military actions the Empire of Japan was planning in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States.

Immediately after the attack on Pearl Harbor, the Japanese pushed on the operations to invade the Philippines. 43 planes bombed Tuguegarao and Baguio in the first preemptive strike in Luzon. The Japanese forces then quickly conducted a landing at Batan Island, and by December 17, General Masaharu Homma gave his estimate that the main component of the United States Air Force in the archipelago was destroyed. By January 2, Manila was under Japanese control and by January 9, Homma had cornered the remaining forces in Bataan. By April 9, the remaining of the combined Filipino-American force was forced to retire from Bataan to Corregidor. Meanwhile, Japanese invasions of Cebu (April 19) and Panay (April 20) met enormous successes. By May 7, after the last of the Japanese attacks on Corregidor, General Jonathan M. Wainwright announced through a radio broadcast in Manila the surrender of the Philippines. Following Wainwright was General William F. Sharp, who surrendered Visayas and Mindanao on May 10.

Then came the Bataan Death March (Japanese:Batān Shi no Kōshin (バターン死の行進)) (1942) was the forcible transfer, by the Imperial Japanese Army, of 60,000 Filipino and 15,000 American prisoners of war after the three-month Battle of Bataan in the Philippines during World War II. The death toll of the march is difficult to assess as thousands of captives were able to escape from their guards (although many were killed during their escapes), and it is not known how many died in the fighting that was taking place concurrently. All told, approximately 2,500–10,000 Filipino and 300–650 American prisoners of war died before they could reach Camp O'Donnell.

Hukbalahap resistance
As originally constituted in March 1942, the Hukbalahap was to be part of a broad united front resistance to the Japanese occupation of the Philippines. This original intent is reflected in its name: "Hukbong Bayan Laban sa mga Hapon", which was "People's Army Against the Japanese" when translated into English. The adopted slogan was "Anti-Japanese Above All".

The Huk Military Committee was at the apex of Huk structure and was charged to direct the guerrilla campaign and to lead the revolution that would seize power after the war. Luis Taruc; a communist leader and peasant-organizer from a barrio in Pampanga; was elected as head the committee, and became the first Huk commander called "El Supremo".

The Huks began their anti-Japanese campaign as five 100-man units. They obtained needed arms and ammunition from Philippine army stragglers, which were escapees from the Battle of Bataan and deserters from the Philippine Constabulary, in exchange of civilian clothes. The Huk recruitment campaign progressed more slowly than Taruc had expected, due to U.S. Army Forces Far East (USAFFE) guerrilla units, of which Ramon Magsaysay was included. The U.S. units already had recognition among the islands, had trained military leaders, and an organized command and logistical system. Despite being restrained by the American sponsored guerrilla units, the Huks nevertheless took to the battlefield only 500 men and much fewer weapons. Several setbacks at the hands of the Japanese and with less than enthusiastic support from USAFFE units did not hinder the Huks growth in size and efficiency throughout the war, developing into a well trained, highly organized force with some 15,000 armed fighters by war's end.

USAFFE and American sponsored guerrillas
After Bataan and Corregidor, many who escaped the Japanese reorganized in the mountains as guerrillas still loyal to the U.S. Army Forces Far East (USAFFE). One example would be the unit of Ramon Magsaysay in Zambales, which first served as a supply and intelligence unit. After the surrender in May 1942, Magsaysay and his unit formed a guerrilla force which grew to a 10,000-man force by the end of the war. Another was the Hunters ROTC which operated in the Southern Luzon area, mainly near Manila. It was created upon dissolution of the Philippine Military Academy in the beginning days of the war. Cadet Terry Adivoso, refused to simply go home as cadets were ordered to do, and began recruiting fighters willing to undertake guerrilla action against the Japanese. This force would later be instrumental, providing intelligence to the liberating forces led by General Douglas MacArthur, and took an active role in numerous battles, such as the Raid at Los Baños. When war broke out in the Philippines, some 300 Philippine Military Academy and ROTC cadets, unable to join the USAFFE units because of their youth, banded together in a common desire to contribute to the war effort throughout the Bataan campaign. The Hunters originally conducted operations with another guerrilla group called Marking's Guerrillas, with whom they went about liquidating Japanese spies. Led by Miguel Ver, a PMA cadet, the Hunters raided the enemy-occupied Union College in Manila and seized 130 Enfield rifles.

Also, before being proven false in 1985, Philippine President Ferdinand Marcos claimed that he had commanded a 9,000-strong force of guerrillas known as the Maharlika Unit. Marcos also used maharlika as his personal nom de guerre, depicting himself as the most bemedalled anti-Japanese Filipino guerrilla fighter during World War II.