Battlecruiser

Battlecruisers were large warships of the first half of the 20th century. They evolved from armored cruisers and in terms of ship classification they occupy a grey area between cruisers and battleships. Different nations built to widely different designs. Some battlecruisers were smaller than heavy cruisers while others were larger than contemporaneous battleships. The chief similarity was the role specification. They were supposed to hunt down and outgun smaller warships (or merchant ships in the case of the pocket battleships), and outrun larger warships that they could not outgun. Originally, to achieve this, they deviated from the standard practice of providing a ship with sufficient armour to protect against its own guns. The weight saving from the reduced armour allowed more powerful engines to be fitted. This idea was mainly conceived by British Admiral Jackie Fisher who believed "speed is the best protection". However, as technology developed design philosophy changed and led to the creation of more heavily armoured ships with less powerful guns. They were given different labels, but essentially performed the same task.

Inter-war years

Post-war developments

Following the end of the war many navies re-evaluated their ship designs. This led to a number of changes as many nations chose to reduce their battlecruiser fleet following the Washington Naval Arms Limitation Treaty rather than scrap valuable battleships.

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British designs

After the war the Royal Navy de-emphasized battlecruisers in the orginal sense of the word and all but three were scrapped by the mid-1930s. In the Royal Navy, the term was applied to ships with heavy armour, but were still capable of speeds in excess of 25 knots. HMS Hood, launched in 1918, was the last British battlecruiser to be completed - however, she was completed with armour that was thought to be capable of resisting her own weapons, the classic measure of a "balanced" battleship. Two battlecruiser hulls were converted into the Glorious-class aircraft carriers. Renown was modernised significantly between 1936 and 1939.

Related Topics:
Royal Navy - HMS ''Hood'' - 1918 - ''Glorious''-class - Aircraft carrier - ''Renown''

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Japanese Designs

• The Imperial Japanese Navy improved the four battlecruisers of the Kongo class by increasing the elevation of the guns to 40 degrees, adding anti-torpedo bulges and additional armour, and building on a "pagoda" mast. The 3,800 tons of additional armour slowed their speed, but between 1933 and 1940 replacement of heavy equipment and an increase in the length of the hull by 26ft (8m) allowed them to get up to 30 knots once again. They were reclassified as "fast battleships".
• The Imperial Japanese Navy scrapped three of the four Amagi class battlecruisers (which were under construction), and converted the fourth, Akagi, into an aircraft carrier in 1927.

US Designs

The United States Navy retasked two battlecruiser hulls as aircraft carriers: USS Lexington and Saratoga were both designed as battlecruisers (the hull designations were originally CC-1 and CC-3) but converted part-way through construction, although this was only considered marginally preferable to scrapping the hulls outright (the remaining four: Constellation, Ranger, Constitution and United States were indeed scrapped). The Lexington class battlecruisers if completed would have been closer in concept to the later fast battleships, being both swift and well-armored without sacrificing firepower. They were planned to be armed with 16" guns and armored against light battleship-caliber weapons; the engines required to propel these vessels at 33 knots (their design speed) made them into fast, flexible and tough aircraft carriers with large growth margins. The heavy use of Saratoga during World War II, however (at one point she and Enterprise were the only carriers in the Pacific), precluded her from having a postwar career.

Related Topics:
United States Navy - USS ''Lexington'' - ''Saratoga''

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Rearmament

As war became more likely nations began to rebuild their forces. At first lip-service was paid to the Treaty of Versailles and the Washington Naval Treaty, but as war became more likely the designs became more ambitious.

Related Topics:
Treaty of Versailles - Washington Naval Treaty

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German designs

• The German pocket battleships (German:Panzerschiffe (armored ship)) (Deutschland, Admiral Scheer, and Admiral Graf Spee), built to meet the 10,000 ton displacement limit of the Treaty of Versailles, were another attempt at a battlecruiser-like concept. Rather than construct a lightweight battleship which sacrificed protection in order to attain high speed, the pocket battleships were relatively small vessels with only six 11 inch (279 mm) guns — essentially large heavy cruisers. They attained fairly high speeds of 26 knots (52 km/h), and reasonable protection, while staying close to the displacement limit, by using welded rather than riveted construction, triple main armament turrets, and replacing the normal steam turbine power with a pair of massive 9 cylinder diesel engines driving each propeller shaft. They were later called "heavy cruisers".
• Two more ships were built later in the 1930s, the Scharnhorst and Gneisenau, which were considerably more powerful. At 38,900 tons full load they were somewhat larger than the French Dunkerque class. They were designed to carry six 15 inch (380mm) guns, but for various reasons they were stuck with nine 11 inch (283mm) guns instead. The Royal Navy categorised them as battlecruisers while the German Navy categorised them as battleships, but effectively they carried the firepower of a heavy cruiser.

French designs

As a response to the German pocket battleships the French decided to built the Dunkerque class in the 1930s. They were labelled "fast battleships" and were armed with 13 inch (330mm) guns arranged in two quadruple turrets located forward. They were considerably larger, faster and more powerfully armed than the ships they were designed to hunt. This last design illustrated inter-war technological developments. The ultimate limit on ship speed was drag from the water displaced (which increases as a cube of speed) rather than weight, so heavier armor slowed World War II battleships by only a couple of knots (4 km/h) over their more lightly armored brethren. Heavy guns mounted on fast and well armoured ships invalidated the concept of the battlecruiser as a ship class in its own right, although the development of the aircraft carrier overshadowed this.

Related Topics:
''Dunkerque'' class - World War II - Aircraft carrier

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