The Buffalo was designed by Dayton T Brown and R D MacCart in response to a 1936 United States Navy requirement for a carrier based fighter. The Buffalo prototype was ordered on 22 June 1936, and made its first flight, as the XF2A-1 (B-139), in December 1937. 54 examples designated F2A-1 (B-239), each powered by a 940 hp R-1820-34 radial engine, and armed with one 7.62mm and three 12.7mm machine guns, were ordered on 11 June 1938, ahead of competing designs from Grumman and Seversky,