Iron Duke-class battleship

Emperor of India off Jaffa in 1920
Class overview
Name	Iron Duke class
Operators	Royal Navy
Preceded by	King George V class
Succeeded by	Queen Elizabeth class
In service	1914–1946
Planned	4
Completed	4
Scrapped	4
General characteristics (as built)
Type	Dreadnought
Displacement	25,000 tons / 29,500 full load
Length	622 ft 9 in (189.8 m)
Beam	90 ft (27.4 m)
Draught	32 ft 9 in (9.98 m)
Installed power	29,000 shp (22,000 kW) 18 water-tube boilers
Propulsion	4 shafts; 4 steam turbines
Speed	21.25 knots (39.36 km/h; 24.45 mph)
Range	7,780 nmi (14,410 km; 8,950 mi) at 10 knots (19 km/h; 12 mph)
Armament	5 × twin 13.5-inch (343 mm) guns 12 × single 6-inch (152 mm) guns 2 × single 3-inch (76 mm) AA guns 4 × 21-inch (533 mm) torpedo tubes
Armour	Belt: 12 in Bulkheads: 8 in Barbettes: 10 in Turrets: 11 in Decks: 2.5 in

The Iron Duke class was a group of four dreadnought battleships built for the British Royal Navy before the First World War. The class comprised four ships: Iron Duke, Marlborough, Benbow, and Emperor of India. Launched from October 1912 to November 1913, this was the third class of Royal Navy super-dreadnoughts. The ships were essentially repeats of the King George V-class battleships; they retained the same ten 13.5 inch (34.3 cm) guns in five twin gun turrets on the centreline. However, the Iron Dukes had improved armour and a more powerful secondary armament of 6-inch weapons instead of the 4-inch mounted on the earlier ships.

The four ships were the most advanced battleships in the Royal Navy at the outbreak of the First World War, though they were soon surpassed by the five ships of the Queen Elizabeth class. They all saw extensive service during the war with the Grand Fleet, where Iron Duke acted as the flagship for the fleet commander, Admiral John Jellicoe. Three of the ships, Iron Duke, Benbow, and Marlborough, were present at the Battle of Jutland; Emperor of India missed the battle by being in dock for periodic refit. The four Iron Duke-class battleships saw limited active duty following the end of the war; they were all demilitarised under the terms of the London Naval Treaty signed in 1930. Iron Duke was reduced to a training and depot ship and lasted in that role until 1946 when she was scrapped. Benbow was scrapped in 1931 and Marlborough followed in 1932. Emperor of India was sunk as a gunnery target in 1931 though was later re-floated to be scrapped in 1932.