The Grumman F3F was the last American biplane fighter aircraft delivered to the United States Navy. It was retired from front line squadrons at the end of 1941 before it could serve in World War II, but it served as the basis for a design that ultimately developed into the monoplane F4F Wildcat. The Wildcat quickly became the primary fighter of the Navy and Marines in the first part of World War II, and continued to be produced throughout the conflict.