	During the Second World War, Tsien worked in the Manhattan Project, which led to America successfully developing the first atomic bomb. In 1943, Tsien and two other members of their rocketry group drafted the first document to use the name Jet Propulsion Laboratory, originally a proposal to the Army for developing missiles in response to Germany's V-2 rocket. This led to Private A, which flew in 1944, and later the Corporal, the WAC Corporal, and other designs.