After entering the Second World War in December 1941, Japanese forces quickly overran most of South East Asia. In 1942, in order to find a shorter and more secure line of supply between Burma (now Myanmar) ad Siam (now Thailand), the Japanese decided to use prisoners of war and civilian labour to build a single line railway to link existing railheads at Thanbyuzayat in the west and Ban Pong in the east. Two forces, one based in Siam and one in Burma, worked from opposite ends of the line, meeting at Konkuita in October 1943.