The Grumman F3F was the last American biplane fighter aircraft delivered to the United States Navy (indeed, the last biplane fighter delivered to any American military air arm), and served between the wars. Designed as an improvement on the single-seat F2F, it entered service in 1936. It was retired from front line squadrons at the end of 1941 before it could serve in World War II, and was first replaced by the Brewster F2A Buffalo. The F3F which inherited the Leroy Grumman-designed retractable main landing gear configuration first used on the Grumman FF served as the basis for a biplane design ultimately developed into the much more successful F4F Wildcat.