The peak of piston-fighter developments during WW II was attained in the North American P-51 "Mustang." The P-51 was built as a low-wing, single-seater, a sleek all-metal stressed-skin fighter. No other aircraft had its combination of speed, range, maneuverability and firepower. Arguably, the "Mustang" was the greatest American fighter of all time and among the best from any nation.