HMS Cossack was a wooden 20-gun corvette, built at Northfleet and launched on 15 May 1854. She was originally laid down for the Imperial Russian Navy as the corvette Witjas, however was confiscated during the Crimean War in 1854.She was commissioned and sailed for the Baltic Sea. During the Crimean War, four vessels of the Royal Navy - Arrogant, Cossack, Magicienne, and Ruby - silenced the Russian batteries at a fort on Gogland on 21 July 1855.