Under Lieutenant General Shōjirō Iida, the IJA 15th Army invaded the southern Burmese province of Tenasserim. The Fifteenth Army consisted initially of the highly regarded 33rd Infantry Division and the 55th Infantry Division. The latter attacked from northern Thailand, which had signed a treaty of friendship with Japan on December 21, 1941. The 15th Army quickly advanced through southern Burma, defeating the British and Indian Burma Army in several engagements, and capturing the capital of Rangoon by March 7, 1942. The Army was reinforced by troops released by the Fall of Singapore and drove northwards into central Burma, defeating the British Burma Corps and the Chinese forces, ultimately driving the Allies from Burma.