China Burma India Theater (CBI) was the name used by the United States Army for its forces operating in conjunction with British and Chinese Allied air and land forces in China, Burma, and India during World War II. Well-known US units in this theater included the Flying Tigers, transport and bomber units flying the Hump, the 1st Air Commando Group, the engineers who built Ledo Road, and the 5307th Composite Unit (Provisional), otherwise known as Merrill's Marauders.