100 Years of Flight "Aces of War" Series. The Supermarine Spitfire was a British single-seat fighter aircraft, used by the Royal Air Force and many other Allied countries during the Second World War, and into the 1950s. It was produced in greater numbers than any other Allied design. The Spitfire was the only Allied fighter in production at the outbreak of the Second World War that was still in production at the end of the war.