HMS Captain was built to a "turret ship" standard common to the late-19th Century. These ships differed from earlier war models in that they held their primary armament (rifled cannon) in traversing turrets which offered for broadened firing arcs as well as protection for the gunnery crew. Warships could now engage from any approach angle instead of hoping to maneuver into position to deliver devastating broadsides. Laid down on January 30th, 1867 by Laird Brothers of Birkenhead, she was launched on March 27th, 1869 and formally commissioned in April of 1870.
As built, HMS Captain carried a crew of about 500 made up of a mix of enlisted and officer personnel. Propulsion was from a reciprocating 4-cylinder horizontal trunk engine developing 5,400 horsepower and this was fed by 8 x Rectangular boiler units all used to drive 2 x Shafts at the stern. Maximum speed (in ideal conditions) reached a useful 15.25 knots. As a "steam-and-sail" warship, HMS Captain retained the form and function of a three-masted sailing arrangement alongside her engine/boiler propulsion scheme. With sails as part of her drive system, she held essentially unlimited range.
Armament was 4 x 12" (25-ton) muzzle-loading rifled guns in two twin-gunned emplacements and 2 x 7" (6.5-ton) muzzle-loaded rifled guns in two single-gunned emplacements. Armor protection reached up to 8" at the belt and 10" at the turrets.
HSM Captain's service life was a short one by any standard for, on September 6th, 1870, she faced steadily increasing winds while sailing with ships of both the Mediterranean and Channel Squadrons. The storm only grew worse into the night until the vessel ultimately rolled over, took on water, and sank with some 480 souls aboard. Twenty-seven managed to survive by clinging to a boat that had become loose during the ordeal.