The Grumman F4F Wildcat was a carrier-based fighter aircraft that began service with both the US Navy and the British Royal Navy in 1940. The British version was initially known as the Martlet. It was first used in combat by the British in the North Atlantic and it was the only effective fighter available to the US Navy and USMC in the Pacific during the early part of World War II. It replaced the Brewster Buffalo as units became available. Total production of the Wildcat was 7,898 aircraft, with 5,927 produced by General Motors. General Motors built Wildcats carried the designation FM-1/2 and operated primarily from escort carriers.