Orders were placed in October, but were suspended in mid-November shortly after the beginning of the Washington Naval Conference which limited battleship sizes.

The orders were cancelled in February 1922 with the ratification of the Washington Naval Treaty which limited construction to ships of no more than 35,000 long tons (36,000 t) displacement.

In 1916 the US had declared its intention to create a Navy "second to none"; the United States Congress had authorized the building of a large number of battleships and battlecruisers.

Two improved Revenge-class hulls were converted during construction into the two Renown-class battlecruisers as emergency builds during the war.

Consequently, a series of designs was prepared of ships with displacements ranging from 53,100 to 44,500 long tons (54,000 to 45,200 t), the only limitations being the ability to use British dockyards and passage through the Suez Canal.

'I3' took another route in saving weight and concentrated the main armament amidships with 'X' turret placed between the forward superstructure and the funnels.

Most immediately noticeable was the concentration of the main battery forward of the bridge and engineering spaces, giving the ships a tanker-like appearance.

Since the G3s were to use existing dockyard facilities, this layout allowed designers to keep the length of the ships, as well as the weight of armour, to a minimum.

The resulting loss of heavy fire astern was considered justifiable since the ships were intended to fight on the broadside.

This provided a better and more stable foundation for fire-control equipment, greatly improved accommodation and protection from the weather.

They were designed to produce a total of 160,000 shaft horsepower (120,000 kW) at a working pressure of 200 psi (1,379 kPa) and temperature of 392 °F (200 °C) with superheat.

Using the 22,000-shaft-horsepower (16,000 kW) cruising turbines, they had an estimated maximum range of 7,000 nautical miles (13,000 km; 8,100 mi) at 16 knots (30 km/h; 18 mph).

[13] The G3s carried a secondary armament of sixteen BL 6-inch Mark XXII guns in superfiring twin turrets instead of casemates or shields – the first time in a British capital ship since the Lord Nelson class of 1904.

They fired a 50-pound (23 kg) high explosive shell at a muzzle velocity of 2,457 ft/s (749 m/s) at a rate of eight to twelve rounds per minute.

[16] The ships were intended to carry four 8-barreled mountings for the 40-millimetre (1.6 in) QF 2-pounder Mark VIII gun (commonly known as a pom-pom), two abaft the funnels and two at the stern.

[18] Like previous classes of British battlecruisers, a pair of submerged, broadside-firing torpedo tubes were planned for these ships.

However, this system of protection required that the armoured citadel should have enough reserve buoyancy to keep the ship stable even if the rest of the hull was riddled by gunfire.

[21] The funnel and boiler room ventilation shafts were surrounded by an armoured box 116 feet (35.4 m) long intended to prevent shells fired from behind the ship reaching 'X' magazine.

The deck's thickness increased to 7 inches (180 mm) partway over the rear engine room and covered the aft 6-inch magazines.

[23] Postwar tests done on a replica of this system showed that filling the buoyancy space with water rather than the sealed steel crushing tubes as used in Hood was just as effective and weighed less.

[24] A compressed air system was fitted to blow the water out of the buoyancy spaces and bring the ship upright in 15 minutes after two torpedo hits.

[23] At the end of the tendering process, the four G3 battlecruisers were ordered on 24 October 1921, without names, from John Brown, Swan Hunter, William Beardmore and Fairfield.

Following the visit of an Admiralty delegation, detailed constructional drawings were sent to John Brown on 3 November with a request that copies be urgently circulated to the other successful contractors.

[25] Work at John Brown progressed on the keel blocks and hull plates for the subsequent two weeks.

Outright cancellation followed on 21 February 1922 with the Washington Naval Treaty signatories agreeing not to build any ship larger than 35,000 long tons (36,000 t).

As no photographic evidence is available to show the ships' keels were actually laid down, it is asserted by at least one historian that none were,[27] although the Admiralty paid John Brown for work and materials which would have been incurred in doing so.