Aircraft development was slow in the interwar years however it accelerated in the late 1930s. At the start of World War II the Royal Navy Fleet fighter was the venerable Fulmar, slow and carrying a crew of 2, it was limited in its manoeuverability. By the end of the War the Navy was operating significantly faster and more capable craft, such as the Spitfire-derived Seafire and the new Hawker Sea Fury, which turned out to be the ultimate piston engined fighter. The Swordfish saw the start of hostilities as an obsolete airframe, yet managed to fill an absolutely essential gap and became part of the machine that won the vital Battle of the Atlantic. It was the only aeroplane available that could operate from small and thus available decks in support of the many convoys that brought the war supplies so vitally needed in Europe.