Even before the Wildcat had been purchased by the U.S. Navy, the French Navy and the Royal Navy Fleet Air Arm (FAA) had ordered the Wildcat, with their own configurations, via the Anglo-French Purchasing Board. The F4F initially known in British service as the Martlet was taken on by the FAA as an interim replacement for the Fairey Fulmar. The Fulmar was a two-seat fighter with good range but operated at a performance disadvantage against single-seater fighters. Navalised Supermarine Spitfires were not available because of the greater need of the Royal Air Force.[14][page needed] In the European theater, its first combat victory was on Christmas Day 1940, when a land-based Martlet destroyed a Junkers Ju 88 bomber over the Scapa Flow naval base.[15] This was the first combat victory by a US-built fighter in British service in World War II.[15]

The type also pioneered combat operations from the smaller escort carriers.[16] Six Martlets went to sea aboard the converted former German merchant vessel HMS Audacity in September 1941 and shot down several Luftwaffe Fw 200 Condor bombers during highly effective convoy escort operations.[17][18] These were the first of many Wildcats to engage in aerial combat at sea. The British received 300 Eastern Aircraft FM-1s giving them the designation Martlet V in 1942–43 and 340 FM-2s, (having changed to using the same name as the US) as the Wildcat VI.[19] Nearly 1,200 Wildcats were flown by the FAA and by January 1944, the Martlet name was dropped and the type was identified as the Wildcat.[20][16][N 2] In March 1945, Wildcats shot down four Messerschmitt Bf 109s over Norway, the FAA's last Wildcat victories