The World at War: The events between 1931 and 1941 that drew the U.S. into war are shown in dramatic detail, starting with the Japanese incursion into Manchuria and ending with the attack on Pearl Harbor. Time: 48 minutes. December 7th: At 7:55 AM on Sunday, December 7th, 1941, the Japanese began an air attack that devastated the Pacific fleet and took the lives of 2,343 servicemen. Time: 37 minutes.