This class of ships was based on the basic design of a J Class of 1937 with a smaller displacement and less complex weapons. The most famous achievement was the Battle of The Barents Sea in December 1942, when Convoy JW51B bound for Russia was attacked by German Battleship Lutzow, Heavy cruiser Hipper and Z class Destroyers. Onslow and her sister ships, heavily outgunned, held off the German attack and saved the convoy.