Japan had already been at war in Manchuria (1931) and China (1937) long before the Second World War started in Europe when Germany invaded Poland on September 1, 1939. By 1941, Japanese military expansion in the Asia-Pacific region had made confrontation and war with the United States increasingly certain.
In preparation for war, on July 26, 1941, General Douglas MacArthur brought the 12,000 strong Philippine Scouts under his command with the 16,000 American soldiers stationed in the Philippines. Even these combined forces were poorly trained and equipped for an adequate defence of the islands against a Japanese invasion.
The attack on the Philippines started on December 8, 1941 ten hours after the attack on Pearl Harbour in Hawaii. As at Pearl Harbour, the American aircraft were entirely destroyed on the ground. Lacking air cover, the American Asiatic Fleet in the Philippines withdrew to Java on December 12, 1941.
Japanese troops landed at the Lingayen Gulf on December 22, 1941 and advanced across central Luzon towards Manila. On the advice of President Quezon, General MacArthur declared Manila an open city on December 25, 1941 and removed the Commonwealth government to Corregidor. The Japanese occupied Manila on January 2, 1942.
MacArthur concentrated his troops on the Bataan peninsula to await the relief of reinforcements from the United States that, after the destruction at Pearl Harbour, could never come. The Japanese succeeded in penetrating Bataan's first line of defense and, from Corregidor, MacArthur had no alternative but to organize a slow and desperate retreat down the peninsula. President Quezon and Vice-President Osmena left Corregidor by submarine to form a government in exile in the United States. General MacArthur escaped Corregidor on the night of March 11, 1942 in PT-41 bound for Australia; 4,000 km away through Japanese controlled waters.
The 76,000 starving and sick American and Filipino defenders in Bataan surrendered to the Japanese on April 9, 1942. The Japanese led their captives on a cruel and criminal Death March on which 7-10,000 died or were murdered before arriving at the internment camps ten days later.
The 13,000 survivors on Corregidor surrendered on May 6, 1942.
For over three years and right to the day of Japan's surrender, the Philippines were to suffer grievously under the depredations of military occupation.
General MacArthur discharged his promise to return to the Philippines on October 20, 1944. The landings on the island of Leyte were accomplished massively with an amphibious force of 700 vessels and 174,000 army and navy servicemen. Through December 1944, the islands of Leyte and Mindoro were cleared of Japanese.
On January 9, 1945 the Americans landed unopposed at the Lingayen Gulf on Luzon and closed on Manila. The Japanese fought desperately, street by street, to hold the city. From February 3 to 23, its liberation took almost a month. When at last the fighting ended in the old Spanish citadel of Intramuros, Manila was in ruins.
Even after the capture of Manila, the Japanese fought on to the bitter end. The Americans made landings to remove the Japanese garrisons on Palawan, Mindanao, Panay and Cebu. The Japanese made their last stand entrenched in northern Luzon. General Yamashita, the Tiger of Malaya, did not surrender in Baguio until September 2, 1945; the same day as General Umezu surrendered formally for Japan on board the USS Missouri in Tokyo Bay.
The liberation of the Philippines was costly. In the Philippines alone, the Americans lost 60,628 men and the Japanese an estimated 300,000. Filipino casualties are estimated at over a million and, sadly, these occurred mainly in the last months of the war when the final outcome had long been decided in any event.
The most serious long term consequence of World War II on the Philippines was to aggravate and embitter its internal social divisions. Prior to his departure for exile in the United States, President Quezon had advised Dr. Jose Laurel to stay behind and cooperate in the civil administration of the Japanese occupation. Whether it was good advice or not, President Quezon had hoped that with the cooperation of Filipinos, the occupation might be less severe. Following Laurel's morally ambiguous example, the Philippine elite, with regrettably few exceptions, collaborated extensively with the Japanese in their harsh exploitation of the country. President Laurel and his wartime government was despised.
On the contrary, the great majority of the Philippine people mounted a remarkably effective resistance to the Japanese occupation. Investigations after the war showed that 260,000 Filipinos had been actively engaged in guerrilla organizations and an even larger number operated covertly in the anti-Japanese underground. By the end of the war, the Japanese had effective control in only twelve of the country's forty-eight provinces.
The largest guerrilla organization was the Hukbalahap (People's Anti-Japanese Army) led by Luis Taruc. He had armed some 30,000 guerrillas who controlled most of Luzon.
By war's end, the members of the resistance firmly believed that the widespread collaboration and corruption of the well-to-do had discredited the ruling elite and that they had thereby forfeited any moral authority to govern.
The United States intended to restore the pre-war Commonwealth government. Luis Taruc and the Huks had well known socialist sympathies and communist associations. Despite their political affiliations, the Huks fully expected the American forces to treat them as allies and war heroes in recognition of their resistance and contribution to the war effort. Instead, the U.S. Army military police set out to disarm them as dangerous insurgents. MacArthur had Taruc arrested and jailed.