Wainwright conducted the heroic defense of Bataan and then of Corregidor after MACARTHUR left the Philippines. He had been posted to the Philippines before, in 1909-10, and had served in France during the Great War. He was sent to the Philippines in September 1940 and in December was ordered to defend northern Luzon. When the Japanese landed at Lingayen Gulf on Luzon in December 1941, Wainwright retreated to Bataan in order to avoid being cut off from the main US forces. When MacArthur was ordered to leave Luzon, Wainwright took over the command and was made a Lieutenant General on 19 March 1942 by ROOSEVELT. He managed to hold out far longer than expected against great Japanese air superiority until ordered to retire to Corregidor on 8 April. There Wainwright and his 15,000 men held out under continuous heavy bombardment from across the straits. On 4 May the Japanese hit the island with 16,000 shells and landed 2000 troops on the night of 5 May. Wainwright surrendered on 6 May and ordered a general surrender of all US and Filipino troops in the Philippines. Guerrilla activities however continued throughout the war.
Wainwright accompanied his men on the Bataan Death March, surviving this to be held as a POW in Manchuria until the end of the war. Still suffering the effects of imprisonment, he stood next to MacArthur on the USS Missouri when the Japanese officially surrendered on 2 September 1945. He was awarded the Congressional Medal of Honor.