Three Eagle Squadrons were formed between September 1940 and July 1941. On 29 September 1942, they were turned over to the Eighth Air Force of the U.S. Army Air Forces and became the 4th Fighter Group. Of the thousands who volunteered, only 244 Americans served with the Eagle Squadrons. Sixteen Britons also served as squadron and flight commanders. The first Eagle Squadron, No. 71 Squadron, was formed in September 1940 as part of the RAF's buildup during the Battle of Britain, and became operational for defensive duties on 5 February 1941. 71 Squadron commenced operations based at RAF Church Fenton in early 1941, before a move to RAF Kirton-in-Lindsey. In April, the squadron transferred to RAF Martlesham Heath in Suffolk for operations over Europe. During May, it suffered its first loss when Mike Kolendorski was killed during a fighter sweep over the Netherlands. The intensity of operations stepped up with a move into No 11 Group of Fighter Command, being based at RAF North Weald by June 1941. On June 21, 1941, 22 year-old Nathaniel Maranz became the first American pilot to become a prisoner of war when he was shot down by a Bf109 over the English Channel and picked up by a German patrol boat after swimming for an hour and a half. He was a prisoner in Stalag Luft III. The squadron's first confirmed victory came on 21 July 1941 when P/O William R. Dunn destroyed a Messerschmitt Bf 109F over Lille. In August, 71 Squadron replaced its Hurricanes and Spitfire Mk IIs, before quickly re-equipping with the latest Spitfire Mk Vs. The unit soon established a high reputation, and numerous air kill claims were made in RAF fighter sweeps over the continent during the summer and autumn of 1941. In December, the squadron was rested back at Martlesham Heath, before a move to Debden in May 1942. The second Eagle Squadron, No. 121 Squadron, was formed at RAF Kirton-in-Lindsey in May 1941, flying Hurricanes on coastal convoy escort duties. On 15 September 1941, it destroyed its first German aircraft. The Hurricanes were replaced with Spitfires, and Spitfire Mk Vs arrived in November 1941. The following month, the squadron moved to RAF North Weald, replacing 71 Squadron. In 1942, its offensive activities over the English Channel included bomber escorts and fighter sweeps. The third and final Eagle Squadron, No. 133 Squadron, was formed at RAF Coltishall in