HMS Cossack was a Cossack-class corvette which was laid down as Witjas for the Imperial Russian Navy.
She was seized due to the Crimean War breaking out whilst she was under construction and taken into service with the Royal Navy.
She was originally laid down for the Imperial Russian Navy as the corvette Witjas, however was confiscated during the Crimean War in 1854.
[2] 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.
Cossack also participated in the blockade of the Courland coast, in July 1855 helped in the capture of Kotka's Island and in August was part of the bombardment of Sveaborg.