Her true ownership was concealed by the fiction that she was being constructed as the Egyptian warship El Monassir. To have been named Mississippi upon delivery to the Confederates, she would have been superior for offshore warfare to all but one of the United States' Navy warships, and thus represented a most serious danger to the Union's control of the seas.
However, effective Federal diplomacy prevented the emergence of this threat. The British government seized the pair of ironclads in October 1863, a few months after their launch and before they could be completed. In early 1864, both were purchased for the Royal Navy, receiving the new names Scorpion and Wivern.
Completed in October 1865, Wivern was assigned to the Channel Fleet until 1868. After a refit that reduced her sailing rig from a bark to a schooner, the Wivern served briefly as a coastguard ship based at Hull and then went into reserve. In 1870 Wivern was brought back into active service and despatched to Hong Kong. She remained in Hong Kong until sold for scrap in 1922, having been reduced to harbor duties from 1904.
One of her commanding officers was Captain Hugh Talbot Burgoyne, VC who was later appointed the commanding officer of HMS Captain. Captain was also a twin turret ship. Unfortunately it was lost in a storm of Cape Finisterre during the night 6/7 September 1870.