The prototype designed by corporation North American after Great Britain requested for the Royal Air Force, It has made the maiden flight at October 26, 1940. The modification P-51B was built in May, 1943. She differed by the installation potent and high altitude Rolls-Royce Merlin engine. P-51B gone into service of 354th Fighter Group of US Air Force in England in December, 1943. These airplanes were widely used as escort fighters and fighters - bombers on all theatres of war up to the end of the WWII.