HMS Wivern, a 2750-ton ironclad turret ship, was built at Birkenhead, England. Ordered by the Confederate government in 1862 as one of two sisters, her true ownership was kept secret under the "cover story" that she was to become an Egyptian warship named El Monassir. Upon delivery to the Confederacy, she was to be named Mississippi. Strong diplomatic pressure by the United States led the British government to seize the two ships in October 1863, while they was fitting out. This action undoubtedly prevented the Confederate Navy from posing an extremely dangerous threat to the Federal blockade, and to the Northern seaboard, as these two ironclads would have been more than a match for all but one of the United States Navy's seagoing warships.

Purchased for the Royal Navy in early 1864, the ship was renamed Wivern and completed in October 1865. She served with the Channel Fleet until 1868. Following a refit that eliminated her square sails in favor of a fore and aft rig, the turret ship served for several months in 1870 as coastguard ship at Hull but then spent nearly a decade in reserve. In 1880, Wivern was returned to active service and sent to Hong Kong as part of that colony's defenses. In 1904 she was reduced to harbor support service. HMS Wivern was sold for scrapping in June 1922.