What was the first operational jet fighter?

The Messerschmitt Me 262, nicknamed Schwalbe (German: "Swallow") in fighter versions, or Sturmvogel (German: "Storm Bird") in fighter-bomber versions, is a fighter aircraft and fighter-bomber that was designed and produced by the German aircraft manufacturer Messerschmitt. It was the world's first operational jet-powered fighter aircraft.

The design of what would become the Me 262 started in April 1939, before World War II. It made its maiden flight on 18 April 1941 with a piston engine, and its first jet-powered flight on 18 July 1942. Progress was delayed by problems with engines, metallurgy, and interference from Luftwaffe chief Hermann Göring and Adolf Hitler. The German leader demanded that the Me 262, conceived as a defensive interceptor, be redesigned as ground-attack/bomber aircraft. The aircraft became operational with the Luftwaffe in mid-1944. The Me 262 was faster and more heavily armed than any Allied fighter, including the British jet-powered Gloster Meteor. The Allies countered by attacking the aircraft on the ground and during takeoff and landing.