Designed by the French naval architect Camille Audenet[1] as an iron-hulled armoured frigate of similar type to the Gloire-class ironclads, although strictly not a sister ship but a unique vessel, Couronne was also intended to fight in the line of battle, unlike the first British ironclads.

[4] The ship's metacentric height of 1.8 metres (6 ft) meant that she rolled less and was a better sea boat than the Gloires.

[3] Her gun ports were slightly higher above the waterline than those of her predecessors, 2 metres (6 ft 7 in), and Couronne took aboard less water as well.

She carried a maximum of 675 tonnes (664 long tons) of coal[4] which allowed her to steam for 2,410 nautical miles (4,460 km; 2,770 mi) at a speed of 10 knots (19 km/h; 12 mph).

[3] Couronne's wrought iron hull was completely protected by armour plates 120 millimetres thick.

[5] On 19 June 1864, Couronne played an incidental role in the Battle of Cherbourg as she escorted the Confederate commerce raider CSS Alabama out of French territorial waters to her fight with USS Kearsarge.

[11] During the Franco-Prussian War the ship was assigned to Vice Admiral Léon Martin Fourichon's squadron that blockaded German ports in the Heligoland Bight in August and September 1870.

The ship was rearmed with an assortment of guns of various calibres for training purposes, replacing Souverain in this role.