In 1942, the Japanese army had captured more than 200,000 Allied prisoners of war and needed a supply route to its frontline troops in Myanmar. POWs and thousands of Asian labourers were ordered to complete a railway linking Thailand and Myanmar that would include the infamous 'bridge on the River Kwai'. Meanwhile, the U.S. was developing a 'smart bomb'. In late 1944, a group of rescued POWs provided the first accurate information about targets along the railway, and the railway was destroyed.