History of the 1921 Project

The euphoria brought about by the victory in the "war to end all wars" was short lived in Britain. By 1921, the United States and Japan were both rapidly expanding their battle fleets. In the United States, the 4 Colorado Class battleships with their 8 x 16" guns were well under way, and 6 Lexington Class battlecruisers and 6 South Dakota Class battleships were to follow. These last two classes of vessels were both over 43,000 tons, and would carry 8 and 12 16-inch guns. In Japan, the 2 Nagato Class 16" gunned battleships were complete, and 2 Tosa Class 16" gunned battleship had been started. Two Amagi Class battlecruisers, of 43,000 tons and carrying 10 x 16" guns, were also underway, and 45,000 ton battleships with 18" guns were being planned.

Clearly another, if less hostile, threat had replaced the threat to Britain's naval supremacy posed by Germany. Japan was clearly expansionist, and the United States' interpretation of "Freedom of the Sea", combined with the refusal to ratify the Treaty of Versailles and join the League of Nations, while not overtly hostile, were definitely of concern.

To match the giants building in America and Japan, Britain began to explore the construction of very large, very powerful ships. Both battleships and battlecruisers were included in the study, with battlecruiser designs being lettered from K backwards to A, and battleship designs being lettered from L to Z. In both cases, a number, either 2 or 3, was added to designate twin or triple turrets.

Preliminary battlecruiser designs K2, K3, I3, and H3, along with battleship designs L2, L3, M2, and M3, were drawn up between October and December 1920. All were for overly large vessels with 18" guns, and all were clearly too large to be realistically built and operated. The DNC accepted a reduction in gun size to 16", and on December 17, 1920, sketch design G3 was accepted. This 48,000 ton, 9 x 16" gun design was fully developed, and four ships were included in the 1921 Estimates. Ordered in October 1921, the G3 ships would most likely have been named Invincible, Indomitable, Inflexible and Indefatigable, though the names St George, St Patrick, St Andrew and St Davis have also been speculated. These last four names may have been for design N3, a class of 48,500 ton, 9 x 18" gunned battleships that were projected to follow the G3.

The G3 design had a novel arrangement for the main turrets which created a 40-degree blind spot aft, and triples were adopted for the first time on a British capital ship to limit the length of the armored hull. The secondary battery of 6" guns was in twin turrets, with a strong battery of AA guns also included. A large tower superstructure of the type found on later battleships was included, as was a transom stern to improve efficiency at high speed. The protection scheme followed the "all-or-nothing" concept, with a 12-14" sloped belt covering the amidships citadel, and only deck armor forward and aft. Horizontal protection was excellent, the heaviest yet in any capital ship. Underwater protection was augmented by bulges, crush tubes, and liquid-loaded compartments. The design was far better protected than the Hood, and was equal to contemporary battleships. They were designated as battlecruisers though, evidently solely on the basis of their 32-knot speed, or perhaps because the N3 battleship design would have been even better protected. The G3 rank as the most powerful capital ships ever designed in Britain. They were a new type, a true fast battleship, and as far advanced over the preceding Hood as that ship was over Renown.

Construction proved to be nearly prohibitively expensive, but guns, turrets, and armor were ordered, and four different yards contracted for the hulls. Work on the G3 class vessels had just barely started when construction was suspended on 18 November 1921. Soon thereafter, the Washington Conference on the Limitation of Naval Arms was convened. The United States, Japan, and Great Britain saw the folly of emptying the national treasuries to pay for an arms race no one wanted, and to build such giant vessels as to make their existing ships obsolete. So all three, plus France and Italy, agreed to cancel the new construction. The G3 were officially cancelled in Feb 1922. The other powers conceded Britain's right to match the 16" guns in service in Japan and the USA, so two 35,000 ton battleships could be built. These vessels, the Nelson and Rodney, used the modified turrets and guns ordered for the first two G3.