HMS Royal Sovereign was originally laid down as a 121-gun first-rate ship of the line of the Royal Navy. She would have mounted sixteen 8 in (200 mm) cannon, 114 32-pounder (15 kg) guns, and a 68-pounder (31 kg) pivot gun. With the rise of steam and screw propulsion, she was ordered to be converted on the stocks to a 131-gun screw ship, with conversion beginning on 25 January 1855. She was finally launched directly into the ordinary on 25 April 1857. She measured 3,765 long tons (3,825 t) burthen, with a gundeck of 240 feet 6 inches (73.30 m) and breadth of 62 feet (19 m), and a crew of 1,100, with engines of 780 nhp.