A memo from Churchill to Rear-Admiral Gordon Moore, Third Sea Lord, on 27 October 1912, stated "the speed and power of the Queen Elizabeths...is sufficient to protect the battle fleet against any turning movement by German battlecruisers.

[5] Influenced by Fisher, Churchill ordered development of the 42-calibre BL 15-inch Mk I gun using the codename "14inch Experimental" in January 1912.

This was a risky decision as development of new heavy guns and their turrets was normally a multi-year project, and a failure would seriously delay the completion of the ships.

[6] The Admiralty decided on the design of the Queen Elizabeths on 15 June 1912, with the decision on whether they would solely use fuel oil deferred to a subsequent meeting.

Eustace Tennyson d'Eyncourt, the DNC who followed Watts, estimated that the change so late in the design process cost some 300 long tons (300 t) that could have been put to better use.

[6] Given the speed of the new ships, envisaged as 25 knots (46 km/h; 29 mph), it was decided that the battlecruiser would not be needed and a fourth battleship would be built instead.

When the Federation of Malay States offered to fund a further capital ship, the Admiralty decided to add a fifth unit to the class, HMS Malaya.

[9] After Jutland Admiral John Jellicoe was persuaded that the slowest ship of this class was good only for about 23 knots (43 km/h; 26 mph), he concluded that, since this should be considered as the speed of the squadron, it would not be safe to risk them in operations away from the main battlefleet.

[12] The turbines were rated at 75,000 shaft horsepower (56,000 kW) at overload and were intended to give the ships a maximum speed of 25 knots (46 km/h; 29 mph),[13] although they fell short of that.

Due to the war only Barham ran her sea trials on a measured course; in August 1916 she reached a top speed of 23.9 knots (44.3 km/h; 27.5 mph) from 70,788 shp (52,787 kW) at deep load.

[14] Fuel storage amounted to 3,400 long tons (3,500 t) of fuel oil which enabled the ships to steam for 5,000 nautical miles (9,300 km; 5,800 mi) at a cruising speed of 12 knots (22 km/h; 14 mph), which fell to 1,600 nautical miles (3,000 km; 1,800 mi) at full speed.

[13] The Queen Elizabeth class was equipped with eight breech-loading (BL) 15-inch Mk I guns in four twin-gun turrets, in two superfiring pairs fore and aft of the superstructure, designated 'A', 'B', 'X', and 'Y' from front to rear.

[16] The gun even remained competitive in the Second World War after receiving further shell upgrades and mountings with greater elevation, and HMS Warspite would eventually record a hit during the Battle of Calabria which to this day is one of the longest-range naval gunnery hits in history - 24,000 metres (26,000 yd).

Captain Morgan Singer, commander of the RN's gunnery school HMS Excellent, criticized this arrangement, saying that it had been proven inefficient in the pre-dreadnought battleships and he recommended using dredger hoists as they were much faster.

His comments were rejected as the Admiralty believed that the guns would only intermittently be in use as destroyers attempted to close to torpedo range and they desired to maintain a break in the cordite supply between the magazines and the battery.

[citation needed] The secondary armament was primarily controlled by directors mounted on each side of the compass platform on the foremast once they began to be fitted in March 1917.

Although most sources and several official papers in the class's Ships Cover[ii] describe her as a further repeat of the Queen Elizabeth design, one historian - Nicholas Lambert - has suggested that Agincourt would have been built on battlecruiser lines.

[25] The cancellation, proposed by Churchill in memoranda of 1 and 14 June 1914, was intended to shave around £900,000 off that year's naval estimates, which had met with resistance from leading members of the ruling Liberal Party.

[26] In the First World War, Queen Elizabeth was detached from the squadron and took part in the Dardanelles Campaign, but missed Jutland as she was undergoing dock maintenance.

Warspite was the most heavily damaged, with her rudder jammed and taking fifteen hits, coming close to foundering.

In spite of this, Malaya prevented an attack on a transatlantic convoy by the modern German battlecruisers Scharnhorst and Gneisenau by her presence.

Warspite survived a direct hit and two near-misses by German glider bombs, while Queen Elizabeth and Valiant were repaired and returned to service after being badly damaged by limpet mines[30] placed by Italian frogmen during a raid at Alexandria Harbour in 1941.

In the Second World War she was mined by Italian frogmen and badly damaged, but did not ground in the shallow water of Alexandria Harbour in 1941.

In the Second World War, she took part in many battles, including Narvik, Cape Matapan, Crete, and Salerno, where she was hit by a glider bomb.

In the Second World War, she took part in the attack on the French Fleet at Mers-el-Kebir, and was mined and damaged at Alexandria in 1941.

[8] She is not to be confused with HMS Agincourt that was ordered by Brazil, sold to the Ottoman Empire while under construction, and seized for use by the Royal Navy before the beginning of the first World War.