The Philippine Islands were one of two major US bases in the Pacific, the other being Pearl Harbor. The Japanese considered the capture of the Philippines crucial for its efforts to control resource-laden Southeast Asia. As opposed to its attack on Pearl Harbor, the Japanese intention was to invade and occupy the Philippines in a campaign that was to last five months.

The flamboyant Douglas MacArthur, a hero of World War I and former Chief of Staff led the defense of the Philippines when the Japanese attacked on 8 December 1941. Despite warnings about the Pearl Harbor attack, the Japanese air forces caught MacArthur's aircraft on the ground resulting in half of his modern bomber and fighter aircraft destroyed. Army Air Forces B-17s attempted to bomb Formosa, but Japanese fighters eliminated them and a Japanese full-scale invasion followed days later.

Japanese forces landed in northern Luzon from Formosa. B-17s and naval attacks tried in vain to stop the invasion, but failed. Poorly trained and equipped Philippine Army units could not halt the Japanese and the American and Filipino forces withdrew, even though they outnumbered the initial Japanese forces. Japanese Army units broke through several defensive lines as they drove on to Manila, which was abandoned by the Americans as Macarthur withdrew to Bataan. The Japanese gradually reduced this pocket until the only American position was Corregidor Island. MacArthur left for Australia, as a direct order from President Franklin Roosevelt and was awarded the Medal of Honor, one of the more controversial aspects of the campaign. With little hope of survival, Corregidor fell, with organized resistance ending on 9 May 1942.

Although a defeat, the American and Filipino defensive efforts upset the Japanese plan for a swift victory and provided time for Australia and the United States to build up their defenses. It also gave hope to the American public that Americans could stand up to Japan, with the "Battling Bastards of Bataan" providing a source of inspiration. Unfortunately, for the survivors of the campaign, it meant a grueling three years of captivity for some. The Bataan Death March was one of the most infamous events in World War II, with Japanese forces responsible for the deaths of about 600 Americans and between 5,000-10,000 Filipino soldiers dying in the march, some summarily executed by beheading.