The battlecruiser (also written as battle cruiser or battle-cruiser) was a type of capital ship of the first half of the 20th century. These were similar in displacement, armament and cost to battleships, but differed in form and balance of attributes. Battlecruisers typically had thinner armour (to a varying degree) and a somewhat lighter main gun battery than contemporary battleships, installed on a longer hull with much higher engine power in order to attain greater speeds. The first battlecruisers were designed in the United Kingdom as a successor to the armoured cruiser, at the same time as the dreadnought succeeded the pre-dreadnought battleship. The goal of the battlecruiser concept was to outrun any ship with similar armament, and chase down any ship with lesser armament; they were intended to hunt down slower, older armoured cruisers and destroy them with heavy gunfire while avoiding combat with the more powerful but slower battleships. However, as more and more battlecruisers were built, they were increasingly used alongside the better-protected battleships.
Battlecruisers served in the navies of the United Kingdom, Germany, the Ottoman Empire, Australia and Japan during World War I, most notably at the Battle of the Falkland Islands and in the several raids and skirmishes in the North Sea which culminated in a pitched fleet battle, the Battle of Jutland. British battlecruisers in particular suffered heavy losses at Jutland, where poor fire safety and ammunition handling practices left them vulnerable to catastrophic magazine explosions following hits to their main turrets from large-calibre shells. This dismal showing led to a persistent general belief that battlecruisers were too thinly armoured to function successfully. By the end of the war, capital ship design had developed, with battleships becoming faster and battlecruisers becoming more heavily armoured, blurring the distinction between a battlecruiser and a fast battleship. The Washington Naval Treaty, which limited capital ship construction from 1922 onwards, treated battleships and battlecruisers identically, and the new generation of battlecruisers planned by the United States, Great Britain and Japan were scrapped or converted into aircraft carriers under the terms of the treaty.
Improvements in armour design and propulsion created the 1930s "fast battleship" with the speed of a battlecruiser and armour of a battleship, making the battlecruiser in the traditional sense effectively an obsolete concept. Thus from the 1930s on, only the Royal Navy continued to use "battlecruiser" as a classification for the World War I–era capital ships that remained in the fleet; while Japan's battlecruisers remained in service, they had been significantly reconstructed and were re-rated as full-fledged fast battleships. Some new vessels built during that decade, the German s and s and the French s are all sometimes referred to as battlecruisers, although the owning navies referred to them as "battleships" (), "armoured ships" () and "battleships" () respectively.
Battlecruisers were put into action again during World War II, and only one survived to the end, . There was also renewed interest in large "cruiser-killer" type warships whose design was scaled-up from a heavy cruiser rather than a lighter/faster battleship derivative, but few were ever begun and only two members of the were commissioned in time to see war service. Construction of large cruisers as well as fast battleships were curtailed in favor of more-needed aircraft carriers, convoy escorts, and cargo ships.
During (and after) the Cold War, the Soviet of large guided missile cruisers have been the only ships termed "battlecruisers"; the class is also the only example of a nuclear-powered battlecruiser. As of 2024, Russia operates two units: the Pyotr Velikiy has remained in active service since its 1998 commissioning, while the Admiral Nakhimov has been inactive (in storage or refitting) since 1999.
Background The battlecruiser was developed by the Royal Navy in the first years of the 20th century as an evolution of the armoured cruiser.Sondhaus, p. 199; Roberts, p. 13 The first armoured cruisers had been built in the 1870s, as an attempt to give armour protection to ships fulfilling the typical cruiser roles of patrol, trade protection and power projection. However, the results were rarely satisfactory, as the weight of armour required for any meaningful protection usually meant that the ship became almost as slow as a battleship. As a result, navies preferred to build protected cruisers with an armoured deck protecting their engines, or simply no armour at all.
In the 1890s, new Krupp steel armour meant that it was now possible to give a cruiser side armour which would protect it against the quick-firing guns of enemy battleships and cruisers alike.Sumida, p. 19 In 1896–97 France and Russia, who were regarded as likely allies in the event of war, started to build large, fast armoured cruisers taking advantage of this. In the event of a war between Britain and France or Russia, or both, these cruisers threatened to cause serious difficulties for the British Empire's worldwide trade.Breyer, p. 47
Britain, which had concluded in 1892 that it needed twice as many cruisers as any potential enemy to adequately protect its empire's sea lanes, responded to the perceived threat by laying down its own large armoured cruisers. Between 1899 and 1905, it completed or laid down seven classes of this type, a total of 35 ships.Lambert 2002, pp. 20–22; Osborne, pp. 61–62 This building program, in turn, prompted the French and Russians to increase their own construction. The Imperial German Navy began to build large armoured cruisers for use on their overseas stations, laying down eight between 1897 and 1906.Gardiner & Gray, p. 142; Osborne, pp. 62, 74 In the period 1889–1896, the Royal Navy spent £7.3 million on new large cruisers. From 1897 to 1904, it spent £26.9 million.Sumida, p. 351, Table 9. Figures are for First-Class Cruisers and exclude armament. Many armoured cruisers of the new kind were just as large and expensive as the equivalent battleship.
The increasing size and power of the armoured cruiser led to suggestions in British naval circles that cruisers should displace battleships entirely. The battleship's main advantage was its 12-inch heavy guns, and heavier armour designed to protect from shells of similar size. However, for a few years after 1900 it seemed that those advantages were of little practical value. The torpedo now had a range of 2,000 yards, and it seemed unlikely that a battleship would engage within torpedo range. However, at ranges of more than 2,000 yards it became increasingly unlikely that the heavy guns of a battleship would score any hits, as the heavy guns relied on primitive aiming techniques. The secondary batteries of 6-inch quick-firing guns, firing more plentiful shells, were more likely to hit the enemy.Sumida, pp. 42–44 As naval expert Fred T. Jane wrote in June 1902,Is there anything outside of 2,000 yards that the big gun in its hundreds of tons of medieval castle can affect, that its weight in 6-inch guns without the castle could not affect equally well? And inside 2,000, what, in these days of gyros, is there that the torpedo cannot effect with far more certainty?Quoted in Sumida, p. 44
In 1904, Admiral John "Jacky" Fisher became First Sea Lord, the senior officer of the Royal Navy. He had for some time thought about the development of a new fast armoured ship. He was very fond of the "second-class battleship" , a faster, more lightly armoured battleship.Roberts, p. 15; Mackay, pp. 212–13 As early as 1901, there is confusion in Fisher's writing about whether he saw the battleship or the cruiser as the model for future developments. This did not stop him from commissioning designs from naval architect W. H. Gard for an armoured cruiser with the heaviest possible armament for use with the fleet. The design Gard submitted was for a ship between , capable of , armed with four 9.2-inch and twelve guns in twin gun turrets and protected with six inches of armour along her belt and 9.2-inch turrets, on her 7.5-inch turrets, 10 inches on her conning tower and up to on her decks. However, mainstream British naval thinking between 1902 and 1904 was clearly in favour of heavily armoured battleships, rather than the fast ships that Fisher favoured.Breyer, p. 48
The Battle of Tsushima proved the effectiveness of heavy guns over intermediate ones and the need for a uniform main caliber on a ship for fire control. Even before this, the Royal Navy had begun to consider a shift away from the mixed-calibre armament of the 1890s pre-dreadnought to an "all-big-gun" design, and preliminary designs circulated for battleships with all 12-inch or all 10-inch guns and armoured cruisers with all 9.2-inch guns.Roberts, pp. 16–17 In late 1904, not long after the Royal Navy had decided to use 12-inch guns for its next generation of battleships because of their superior performance at long range, Fisher began to argue that big-gun cruisers could replace battleships altogether. The continuing improvement of the torpedo meant that submarines and destroyers would be able to destroy battleships; this in Fisher's view heralded the end of the battleship or at least compromised the validity of heavy armour protection. Nevertheless, armoured cruisers would remain vital for commerce protection.Mackay, pp. 324–25; Roberts, pp. 17–18; Sumida, p. 52
Fisher's views were very controversial within the Royal Navy, and even given his position as First Sea Lord, he was not in a position to insist on his own approach. Thus he assembled a "Committee on Designs", consisting of a mixture of civilian and naval experts, to determine the approach to both battleship and armoured cruiser construction in the future. While the stated purpose of the committee was to investigate and report on future requirements of ships, Fisher and his associates had already made key decisions.Roberts, p. 19 The terms of reference for the committee were for a battleship capable of with 12-inch guns and no intermediate calibres, capable of docking in existing drydocks;Breyer, p. 115 and a cruiser capable of , also with 12-inch guns and no intermediate armament, armoured like , the most recent armoured cruiser, and also capable of using existing docks.
First battlecruisers Under the Selborne plan of 1903, the Royal Navy intended to start three new battleships and four armoured cruisers each year. However, in late 1904 it became clear that the 1905–1906 programme would have to be considerably smaller, because of lower than expected tax revenue and the need to buy out two Chilean battleships under construction in British yards, lest they be purchased by the Russians for use against the Japanese, Britain's ally. These economic realities meant that the 1905–1906 programme consisted only of one battleship, but three armoured cruisers. The battleship became the revolutionary battleship , and the cruisers became the three ships of the . Fisher later claimed, however, that he had argued during the committee for the cancellation of the remaining battleship.Sumida, p. 55