On 1 December 1941, I-55 departed Sanya to begin her first war patrol, and on 7 December she deployed north of Kuantan with I-53 and I-54 in a patrol line to support the Japanese invasion of Malaya, which was scheduled to begin the following day. Hostilities began in East Asia on 8 December 1941 (7 December across the International Date Line in Hawaii, where Japan began the war with its attack on Pearl Harbor), and on 9 and 10 December I-55 participated in attempts to intercept a British Royal Navy task force centered around the battleship HMS Prince of Wales and battlecruiser HMS Repulse before they could threaten Japanese invasion convoys, although Imperial Japanese Navy torpedo planes sank the two ships off the Malayan Peninsula on 10 December before the submarines could engage them.[1]