At the outbreak of World War II the main plane in the Royal Navy air arm was the Swordfish biplane. That changed rapidly as the British motor industry had already started to supplement aircraft manufacturing for the RAF and the Hurricane came into service followed by the Spitfire; that outperformed every fighter in the European theater except the American P-51. At the beginning of the Battle of Britain the RAF was outnumbered by 4:1 The change in targets to cities by the Luftwaffe gave the RAF fighter Command the respite it needed and eventually win the Battle of Britain. During the following Blitz, British cities were bomber over and over with London bombed 57 straight days. By May on 1941, the RAF had lost 792 planes and the Luftwaffe almost 1,400.The RAF Coastal Command was instrumental in the battle against German U-boats in the Atlantic and the planes from the carrier Ark Royal sank the dreaded German battleship Bismarck.