On D-Day+2 (8 June) the wing shot down three Bf 109s over the invasion beaches without loss, the first one credited to Beamont and the first to a Tempest. From his airfield at Newchurch, Beamont witnessed the first intrusion by V-1 flying bombs as they flew towards London at dawn on 14 June; two days later (16 June) his wing was switched to intercepting them. In the following days, he and his pilots would trial attack tactics by day and discuss their effectiveness in the evening. For instance, Beamont discovered first hand that attacking a V-1 at close range could result in a hazardous explosion. He established that the best attack was to approach from astern at an acute angle with the cannons synchronised to 200yds (180m). On at least one occasion Beamont defeated a V-1 by carefully sliding his wing-tip under that of the V-1 and flipping it. His fifth V-1 kill on the evening of 19 June made him the first V-1. ace. By the end of the V-1 campaign, 150 Wing had shot down 638, with Beamont accounting for 32. Around this time Beamont met Ernest Hemingway, who had flown over from America to report on the D-Day invasion and spent time in 150 Wing's officer's mess. On 2 October 1944, now based on the continent at Volkel, the Netherlands, he achieved his ninth and final kill of the war when he shot down a Fw 190 near Nijmegen. On 12 October, on his 492nd operational mission, while attacking a heavily defended troop-train near Bocholt his Tempest's radiator was hit by flak. He crash landed without injury and became a prisoner of war (PoW). Confined firstly to Stalag Luft III at Żagań in Lower Silesia, then to Stalag III-A at Luckenwalde, Brandenburg, he remained a PoW until the end of the war in Europe (May 1945). Beamont and other POWs were detained for a few weeks by Soviet forces, and repatriated in late May. AT RAF Chilbolton Beamont formed the first wing of Hawker Tempest IIs in preparation for planned invasion of Japan. The Tempests were to escort bombers of Tiger Force over Japan. The operation was cancelled following the bombing of Hiroshima and Nagasaki. In May 1946 he was awarded the American Distinguished Flying Cross.