During World War II the Japanese Empire invaded Burma, starting at Mawlamyine in January 1942. The Japanese army, numbering 18,000 against 7,000 British defenders, quickly captured Mawlamyine, forcing the British to retreat across the Salween to Martaban. On February 10–11 the Japanese crossed the Salween and the British fled, unprepared for a siege. The Japanese blockaded the Burma Road constructed in 1938 during the Second Sino-Japanese War, forcing the British to transport military supplies to China across the eastern Himalayas ("The Hump"). The retreating Allied army (primarily Chinese) stopped the Japanese advance at the Salween River on May 5, 1942. After blowing all the bridges crossing the river, the Chinese took defensive positions on the east bank along a front, at which point the fighting reached a stalemate.