In March 1918, the United States Army Air Service requested several American aircraft manufacturers to design a new fighter, to be powered by a water-cooled 300 hp (220 kW) Wright-Hispano H, a license-built Hispano-Suiza 8, to replace the French-built SPAD XIII.

Powerplant was the expected Wright-Hispano water-cooled V-8 engine driving a two-bladed propeller and cooled by a radiator mounted on the center-section of the upper wing.

The prototypes were plagued with fuel leaks and suffered serious engine vibration, while maintenance was difficult, often requiring holes to be cut in the fuselage structure to allow access.

[11][15] Boeing credits this contract with rescuing the company from financial difficulties following the cancellation of orders after World War I, and with being the impetus for its rise as a premier manufacturer of military aircraft.

[17][20] Data from United States Military Aircraft Since 1909 [24]General characteristics Performance Armament Notes Media related to Thomas-Morse MB-3 at Wikimedia Commons