On 25 January 1905 the full Committee on Designs decided that the new armoured cruiser should be designed for 25 knots when carrying 1000 tons of coal. A model of the cruiser, by then named Invincible, was ready for inspection on 6 February. It showed two tripod masts, a heavy mast aft to handle the four heavy boats and a light one forward to handle the light boats. Each mast would carry a fire-control position. At this point the anti-torpedo (boat) battery was twenty 12pdrs: seven each on the forward and aft flying decks (the upper decks of the superstructure, carrying the boats), two on the forecastle deck and one on each turret).
As in the Dreadnought design, it was decided to reduce some armour to provide 2½in underwater protection to the magazines. The width of the 6in amidships belt was reduced by 6in and 50ft of forward 4in armour reduced to 3in; 12in turret armour was reduced from 8in to 7in on sides and rear; barbettes were reduced from 8in to 7in; and the heights of the centres of the forward 12in guns above water were reduced from 34ft to 32ft. As of March 1905 the ship was expected to displace 16,750 tons and the anti-torpedo battery was eighteen 12pdrs. Expected speed was 25 knots (rather than the 25.5 knots originally desired). The Board formally approved the proposed outline design on 20 March 1905.
Like their pre-dreadnought predecessors, Dreadnought and Invincible used coal both for propulsion and for a degree of protection against both shellfire and underwater explosions. By the time they were built, the Royal Navy was burning oil as well as coal in its boilers, so both stowed oil in their double bottoms. The Royal Navy rejected above-water oil stowage for fear of fire; it took many years to realise that oil was a useful buffer against torpedo hits. (John Roberts)
The main change after approval was in the anti-torpedo battery. Torpedo defence guns were grouped for control, each group provided with its own searchlight (DNO wanted twelve groups, each covering a 30° arc, each able to reinforce the next group on either side). Guns on centreline turrets could not be used at night due to the blast of neighbouring superstructure guns and the glare of searchlights, but they might be retained for use during a day action. They were not included in DNO’s list, but he did place two guns each atop ‘B’ and ‘C’ turrets and two guns on the forecastle as in Dreadnought. The searchlights were crucial, because it was assumed that most torpedo attacks would be made at night, before or after a battle. However, a battlecruiser also had to be able to deal with day attacks, because she might operate alone near an enemy base. Ideally groups should overlap for mutual support. Reviewing the design in May 1906, DNO objected to its weak end-on fire. Only one searchlight would bear right aft.
This discussion led to rearrangement of the anti-torpedo guns, two atop each turret. This arrangement offered each 12in gun a practice gun without any need for sub-calibre guns. It was also claimed that turret-top guns were less liable to damage during a day action, as only a direct hit could affect them. By this time trials against the old destroyer Skate had shown that the 12pdr might not be enough to stop an oncoming torpedo boat before it could launch its weapons. DNO’s preferred weapon was a high-velocity 4in/50 firing a shell more than twice as heavy as that of the 12pdr; he proposed sixteen of them, each group associated with a 36in electrically-controlled searchlight. In 1906 this weapon was still in the design stage. Because the armoured cruiser project was so urgent, the ships were armed with the existing low-velocity 4in gun (2300ft/sec vs 2600ft/sec for the 12pdr). The paired turret-top arrangement was retained. HMS Excellent (the gunnery school, hence test facility) commented that the turret-top guns would be very well placed to repel torpedo craft by day and that training the turret would give them a very wide arc.6 Blast screens could protect the 4in guns from 12in gun blast. The problem of glare from the searchlights was more complex.7 Substitution of 4in for 12pdrs added 65 tons, which was taken from the Board Margin. Inflexible, the ship with electrical rather than hydraulic mountings, had to carry another 180 tons. All the ships had to add 80 tons to balance their 12in mountings.
The electric gun mountings in Inflexible were unsuccessful and by February 1912 plans called for converting them to hydraulics, as in the other ships of the class. That took six months. At the same time, First Sea Lord recommended that each turret be fitted with a rangefinder, so that it could be self-contained.8 Initial plans were to provide only ‘A’ turret with a rangefinder.
THE 1905–6 programme included four armoured ships (Dreadnought and three Invincibles). In November 1905 the Tory Government called an election. On 30 November 1905 the outgoing First Lord Cawdor, who had succeeded Selborne, produced a memorandum on future building programmes which could be viewed as an election manifesto.1 This Cawdor Memorandum presumably reflects not only First Lord’s own views, but even more strongly those of Fisher. Cawdor pointed out that even though Japanese victory over Russia might seem to have ended the need to build new capital ships, technology was changing and it was vital to maintain superiority in each new type which appeared. That clearly referred to the way in which HMS Dreadnought had in effect reset the standard of sea power. Cawdor therefore proposed a policy: ‘build few – build fast, each improving on the last’. Through 1908 he envisaged an annual programme of four armoured ships. ‘Inasmuch as the armoured cruisers will be equal in offensive strength to any battleships then completed, they may fairly be counted on as equivalent to battleships.’ Moreover, it was now possible to build ships much more quickly: for the first few years the output of new ships would be at least double that of past programmes and far beyond what any foreign power could achieve. Cawdor also envisaged a merger of the battleship and armoured cruiser, referring to an idea closely examined by the French only three years earlier and also to the Italian Regina Elena class. On this basis the 1906–7 programme was sketched in the autumn of 1905.
New Zealand shows wartime modifications in a photograph taken in 1919, when she visited Australia with Admiral Jellicoe on board for his survey of Empire naval requirements. She had been refitted specifically for the tour between December 1918 and February 1919. The range dial on her foretop was removed and the deflection scale on ‘A’ turret painted out. The lower 4in gun in the forward group on each side was removed, the forward superstructure enlarged to provide accommodation and the flying-off platforms atop ‘P’ and ‘Q’ turrets were removed. Surviving wartime changes included the director bracketed to the foremast under the foretop, the large foretop rangefinder (presumably in a stabilised Argo mounting like those mounted atop the conning towers of later ships), the rangefinder atop the roof built over the compass platform and the relocated searchlights, all 36in rather than twin 24in. (Alan C Green via State Library of Victoria)
HMS Bellerophon was the first battleship following Dreadnought; she appeared to be simply an improved version of the latter. That hid the reality that she was quickly designed once it became clear that it was impossible to build the alternative ‘fusion’ design, X4. She is shown in June 1909. The apparently greater height of the fore-funnel is deceptive.