HMS Iron Duke was the last of four Audacious-class central battery ironclads built for the Royal Navy in the late 1860s.

Completed in 1871, the ship was briefly assigned to the Reserve Fleet as a guardship in Ireland, before she was sent out to the China Station as its flagship.

[1][9] The wrought iron waterline armour belt of the Audacious class covered the entire length of the ships.

During the First Reserve Squadron's summer cruise on 1 September, she was en route with three other ironclads between Dublin and Queenstown (now Cobh).

In a thick fog, the ship accidentally rammed her sister, Vanguard, off Kish Bank, in Dublin Bay.

The ram also damaged the watertight bulkhead between Vanguard's engine and boiler rooms which flooded both compartments and prevented her crew from using her steam-powered pumps.

[15] Following the collision, Iron Duke was overhauled at Plymouth Dockyard, with attention being given to the watertight doors on board.

She was 3 nautical miles (5.6 km) out when it was found that the main sluice valve had been left open and she was sinking.

[17] Following the loss, Iron Duke replaced Vanguard as the guardship at Kingstown, County Dublin, where she received the latter's crew and remained until July 1877 when the ship began a lengthy refit that lasted until August 1878.

Iron Duke then departed Plymouth on 4 August, bound for the China Station;[19] en route, she pulled the P&O steamship Bengal off a reef in the Red Sea[18] on 7 September after two days' effort.

The ship struck a rock off the coast of Hokkaido en route to Aniva Bay, Sakhalin Island, on 30 July 1880.

She floated off on 1 August after another ship had also grounded while trying to assist; her repairs required a month in drydock in Hong Kong.

On 28 January 1881, Coote hauled down his flag and was relieved by Vice-Admiral George Willes, the new Commander-in-chief, of the China Station.

[22] Iron Duke returned home in January 1883 and began a lengthy refit that included the replacement of her boilers.

[23] After the ironclad Sultan broke loose from her anchors in Lisbon on 24 December 1886 during a gale and accidentally rammed and sank the French steamship Ville de Victoria, Iron Duke's crew manned one boat in search for survivors, although it is uncertain how many they saved.

[24] The following year, Iron Duke participated in Queen Victoria's Golden Jubilee Fleet review on 1 July 1887 at Spithead.