The U.S. entered World War I in April 1917 with no combat ready aircraft. In the spring of 1918, the Army asked the Thomas-Morse Company of Ithaca, New York, to develop a single-engine pursuit aircraft superior to the French SPAD. The first prototype of the MB-3 did not make its first flight until 1919 when the war was over. The Army was impressed with the aircraft and ordered 50 from Thomas-Morse; a further 200 improved MB-3A models were ordered from Boeing in 1920. Boeing got the contract because the Army used a competitive bidding process and Boeing had the lowest bid. The MB-3As remained in service as a advanced trainer, designated MB-3M, at Kelly Field until 1928.