The Moro Muslims of Mindanao and Sulu took up arms and fought hard against the Japanese invasion and helped defeat the Japanese occupation. Some of the Moros had been fighting the Americans just weeks before the Japanese invaded and proceeded to direct their fight against the new invaders as well. Sultan Jainal Abirin II of Sulu opposed the Japanese invasion. The violent armed struggle against the Japanese, Filipinos, Spanish, and Americans is considered by current Moro Muslim leaders as part of the four centuries long "national liberation movement" of the Bangsamoro (Moro Nation). The 400-year-long resistance against the Japanese, Americans, and Spanish by the Moro Muslims persisted and morphed into their current war for independence against the Philippine state.
The Tausug Moros lived in the Sulu archipelago, traditionally ruled by the Sulu Sultanate, the Maguindanaon Moros lived in on Mindanao, traditionally ruled by the Maguindanao Sultanate, and the Maranao Moros lived around Lake Lanao, traditionally ruled by the Confederation of sultanates in Lanao (Pat a Pangampong a Ranao). They were invaded by the Americans in the Moro Rebellion and annexed into the Philippines. Among the anti-Japanese resistance the Tausug leader was Sulu Sultan Jainal Abirin II, the Chinese-Maguindanaon leader Datu Gumbay Piang, and Maranao leaders were Datu Busran Kalaw, Salipada Pendatun, Sultan Alonto, Sultan Dimaporo, and many others. Salipada Pendatun's brother-in-law Major Datu Udtug also fought against the Japanse and in Cotabato the focal area of anti-Japanese resistance was Papalungan.
The Moro juramentados performed suicide attacks against Japanese troops, as they had against the Spanish, Americans and Filipinos, but did not ever attack the Chinese since the Chinese were not considered enemies of the Moro people. The Japanese responded to these suicide attacks by massacring all the relatives of the attacker. The Japanese were attacked with bayonets, machine gun, bows, spears, clubs, kris and bolo during the invasion.
An American POW Herbert Zincke recalled in his secret diary that the Japanese guarding him and other prisoners were scared of the Moro warriors and tried to keep as far away from them as possible to avoid getting attacked. The American First Lieutenant Mel Amler recalled that some of the Moros would sometimes attack and stab Japanese, Filipino, and Americans, fighting all of them at once. Neither the Moros nor the Japanese respected the Geneva Convention in regards to not attacking medics, the Moros out of ignorance and the Japanese because they did not sign the treaty. American General Robert L. Eichelberger saw a Japanese soldier who was captured by the Moros and feared being tortured at their hands, and he wanted Eichelberger to kill him to stop it from happening. The American POW Victor L. Mapes saw Japanese troops getting ambushed and slaughtered by Moro fighters with kris blades. The Moros were skilled at melee combat, with some Moros deliberately impaling their own shoulder on Japanese bayonets and grabbing it to make it stay in place while killing the Japanese soldier using a bayonet or bolo with their other hand.
The bladed weapons like spear, tabaf, campilan, barong, and kris were used by Moro Lanao against the Japanese according to Sa Ramain to compensate for them having no guns.
Anti-Japanese Moro units like the Maranao Militia were led by Salipada Pendatun, another anti-Japanese Moro unit, the Moro-Bolo Battalion was led by Datu Gumbay Piang, consisting of about 20,000 men. Gumbay Piang's Cotabato Moros used Bolo knives to fight the Japanese, and swore that they would "fight to the last". An oath was sworn by Alonto, the Sultan of Ramain, and 10,000 other Moros in Lanao that they would fight to drive the Japanese out, and sent in a message that said "We have prepared our bladed weapons because we lack firearms, and with sharp kris, barong, campilan, tabas and spear we will attack or defend as ordered," "and no mercy asked." Alonto said "all fighting men of Lanao would like to sign their names, but they are too many". They promised to fight to the death against the Japanese and "swore upon the Koran". The Japanese demanded that all the natives in the Philippines hand over any implement which was a weapon or could be utilized as a weapon, including Bolo knives, and the Japanese may have issued this order because of the Moro pledge to fight the Japanese since the Moros were skilled with bladed weapons. The American Captain Edward Kraus recommended Moro fighters for a suggested plan to capture an airbase in Lake Lanao for eventually driving the Japanese occupiers out of the Philippines.
The Moro Datu Pino sliced the ears off Japanese and cashed them in with the American guerilla leader Colonel Fertig at the exchange rate of a pair of ears for one bullet and 20 centavos.
The Moro Maranao Datu Busran Kalaw was xenophobic against all foreigners, and "fought both the Americans and the Japanese". The Japanese Major Hiramatsu, a propaganda officer, tried convincing Kalaw that Japan was bombing the American mainland. The Japanese tried to convince Kalaw to join their side as "brother Orientals". Kalaw sent a response which goaded Major Hiramatsu into sending a force of Japanese soldiers to attack him, whom Kalaw butchered completely with no survivors. Kalaw's response also said that "Our ambushes will at least teach you respect for the Moros". Amer Manalao Mindalano, Datu Busran Kalaw, and Sultan Mohamad Ali Dimaporo were all Maranao Moro Muslim guerilla leaders who fought against the Japanese. Mohamad AH Dimaporo, Domocao Alonto, and Busran Kalaw commanded the biggest resistance forces in the region. As a famous guerilla leader whose assaults were a "thorn in the side of the Japanese", Kalaw's anti-Japanese speech in Tamparan which galvanized the people of Tamparan in their struggle. Kalaw objected to the decision to surrender to the Japanese by the American General Guy O. Fort, the commander of USAFFE forces in Lanao in 1942. After USAFFE surrendered, Kalaw and other Maranao Moro leaders like Naguib Juanday, Manalao Mindalano and others organized their own resistance movements to fight the Japanese. Kalaw claimed that after USAFFE's surrender to the Japanese, General Guy O Fort let the Maranaos claim the USAFFE rifles. Among the anti-Japanese resistance, the "strong leaders" had Kalaw among their number.
The Maranao Moros fought the Japanese 108th Division almost every week from 1943 to October 1944 in Lanao (southern Mindanao). 130 Japanese troops were slaughtered at towns around Lake Lanao on September 12, 1942, leading the Japanese to avoid the area, so this freed Manalao Mindalano and Busran Kalaw's Maranao forces to fight the Japanese in the coastal north region.
The Cotabato and Lanao based anti-Japanese Maranao Muslim guerilla leaders included " Manalao Mindalano, Busran Kalaw of Momungan, Datu Laguindas of Ganasi, Joseph Sanguilla of Mumay and Madalum and Datu Buntalis of Masiu." Busran Kalaw was a teacher before the war and he became a Major in the MMF anti Japanese guerilla force. Kalaw had also been the town of Momungan's municipal treasurer. The resistance leader Kalaw's wife was a Christian Visayan while he was a Muslim Maranao. The Pangampong also provided other Datus and Sultans who commanded along with Busran Kalaw's resistance forces.
The Japanese Captain Taka Ichi was goaded by the Moro Datu Lacub and Datu Dimalaung of Basak into attacking them, after which the Datus slaughtered all of the 125 Japanese soldiers whom Taka Ichi commanded.
Davao in Mindanao had a large population of Japanese immigrants who acted as a fifth column, welcoming the Japanese invaders during World War II. These Japanese were hated by the Moros and disliked by the Chinese. The Moros were judged as "fully capable of dealing with Japanese fifth columnists and invaders alike." The Moros were to fight the Japanese invaders when they landed at Davao on Mindanao. The Japanese went back to their ships at night to sleep since the Moros struck so much fear into them, even though the Moros were outnumbered by the Japanese.
It was reported that most of Mindanao was dominated by Moro, Filipino, and American guerilla forces during the Japanese occupation. The Moros had cleared the Japanese out from the Muslim areas of Mindanao six months before America returned to liberate the Philippines at the Battle of Leyte. The Moros then joined in on the battle to liberate the rest of Mindanao from the Japanese in 1945. The Moro Muslims nearly exterminated all occupying Japanese soldiers in Sulu before the return of the Americans and the Japanese were constantly attacked by Muslim guerillas.
Nur Misuari's Moro National Liberation Front faction stated that the Japanese "exhibited tyranny, cruelty and inhumanity at its lowest level", and "had to suffer their worst defeat and highest death mortality at the hands of the Bangsamoro freedom fighters". The MNLF wrote that compared to the Japanese casualty rate in the Visayas and Luzon, the amount of Japanese imperialists slaughtered by the Moro freedom fighters was greater by the thousands and that there was no capitulation like the "Fall of Bataan" to the Japanese by the Moros while the Luzon Filipinos submitted. The MNLF said that the Japanese, American, and Spanish cruelty has been continued by Filipino rule.
A Muslim cleric from the Sulu in the Philippines, Imam Marajukim, helped supply Chinese and Suluk Muslim guerillas under Albert Kwok on British Borneo who were fighting the Japanese. Suluks were described as "strongly disposed to be anti-Japanese". Imam Marajukim helped the Chinese secure the indigenous participation in the uprising by Panglima Ali's Suluks, Mantanni and Danawan (Dinawan) islands Binadan inhabitants and Oudar Islanders under Orang Tuah Arshad.
The Imperial Japanese Navy medic Akira Makino revealed that while he was stationed on Mindanao at Zamboanga from December 1944 to February 1945, he and other Japanese troops in his unit killed Moro Muslim prisoners by beheading or performed vivisections on them, cutting them open while they were alive to study their internal organs, and the Japanese also forced the Moros to dig their own graves.
Some of the weapons used by the Moros against the Japanese were again used by them in the Moro insurgency in the Philippines.