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. Iron Duke returned four years later and resumed her duties as a guardship. She accidentally rammed and sank her sister ship, Vanguard, in a heavy fog in mid-1875 and returned to the Far East in 1878. The ship ran aground twice during this deployment and returned home in 1883. After a lengthy refit, Iron Duke was assigned to the Channel Fleet in 1885 and remained there until she again became a guardship in 1890. The ship was converted into a coal hulk a decade later and continued in that role until 1906 when she was sold for scrap and broken up.

The Audacious-class ironclad battleships were designed by Sir Edward Reed at the request of the Board of Admiralty to serve as second-class battleships on distant foreign stations.