Japan sought domination of the Pacific during World War II. Japan opened its doors to the outside world in the mid-1800s, and before the century was over, they had begun to expand. In 1931, Japan invaded Manchuria and prepared to conquer China. Late in 1940, this military powerhouse allied with Germany and Italy, creating the Axis powers of WWII. This gave them the pretext they needed to invade European colonies in the Pacific, beginning with French Indochina. After a decade of regional aggression, Japan attacked Pearl Harbor and other Allied possessions in the Pacific on December 7, 1941, and soon gained an empire stretching over 2.8 million square miles. America lost the critically important Philippine Islands in 1942, leaving thousands of troops to suffer the Bataan Death March. The death rate for American POWs in the Pacific was about 40%. After the Doolittle Raid in 1942, the Japanese wanted revenge and planned to wipe out America's aircraft carriers at the Battle of Midway. Instead, American planes decimated the Japanese navy and gained the upper hand. The Allies began island hopping to approach Japan. Japan defended its territory by using kamikaze attacks and fighting to the last man. High casualties at Iwo Jima and Okinawa caused President Harry Truman to reconsider the planned invasion of Japan, especially when he learned about the Manhattan Project.