De Havilland Mosquito
Jet aircraft first engaged in air combat on 26 July 1944, when "Leutnant" Alfred Schreiber, flying Messerschmitt Me 262 A-1a "W.Nr. 130 017" (German language: "Werknummer" – factory serial number), attacked an unarmed photo-reconnaissance De Havilland Mosquito PR Mk XVI, of No. 540 Squadron RAF, over the Alps. Some sources refer to this as the first victory in air combat by a pilot of a jet fighter, although the crew of the damaged Mosquito managed to return to an Allied airfield in Italy.