Capital ship

Aircraft carriers are the main capital ships of most blue-water navies

The capital ships of a navy are its "important" warships; the ones with the heaviest firepower and armor. A capital ship is generally a leading or a primary ship in a fleet.

There is usually no formal criterion for the classification, but it is a useful concept when thinking about strategy, for instance to compare relative naval strengths in a theatre of operations without having to get bogged down in the details of tonnage and gun diameters.

A good example of this is the Mahanian doctrine, which was applied in the planning of the defence of Singapore in WWII, where Royal Navy had to decide the allocation of their battleships and battlecruisers between the Atlantic and Pacific theatres. The Mahanian doctrine was also applied by the Imperial Japanese Navy which led to their pre-emptive move to attack Pearl Harbor and the US pacific battleships. Another instance is the US Navy's chief warships being deployed in the Pacific, such as aircraft carriers and battleships. Although the United States and the United Kingdom agreed upon a Germany first grand strategy, Germany's surface fleet was small and the escort ships used in the Second Battle of the Atlantic were mostly destroyers and destroyer escorts to counter the U-boat threat.

Era of Sail

Before the advent of the all-steel navy in the late 19th century, a capital ship was a warship of the First, Second or Third rates:

• 1st Rate: 100 or more guns, typically carried on three or four decks. Four-deckers tended to have problems with the waterline and the lowest deck could seldom fire except on the calmest of seas.
• 2nd Rate: 90–98 guns
• 3rd Rate: 64 to 80 guns (although 64-gun third-raters were very small and not very numerous in any era).

Frigates were ships of the fourth or fifth rate; a corvette was a ship of the sixth rate.

Battleship / Battlecruiser

The definition of "capital ship" was formalized in the limitation treaties of the 1920s and 30s; see Washington Naval Treaty, London Naval Treaty, and Second London Naval Treaty. This applied mainly to ships resulting from the dreadnought revolution; dreadnought battleships (also known first as dreadnoughts and later as battleships) and battlecruisers.

In the 20th century, especially in World Wars I and II, typical capital ships would be battleships and battlecruisers. All of the above ships were close to 20,000 tons displacement or heavier, with large caliber guns and heavy armor protection. Heavy cruisers, despite being important ships, were not considered capital ships.

An exception to the above in World War II was the Deutschland-class cruiser. Though this class was technically similar to a heavy cruiser, albeit with considerably heavier guns, they were generally regarded as capital ships (hence the British label "Pocket battleship"). The Alaska-class cruisers, despite being oversized heavy cruisers and not true battleships/battlecruisers, were also considered by some to be capital ships.

During the Cold War, a Soviet Kirov-class large missile cruiser had a displacement great enough to rival WWII-era capital ships, perhaps defining a new battlecruiser for that era. However, others point out that the Kirov is just a supersized guided-missile cruiser.

Aircraft carrier

It took until late 1942 before Aircraft carriers were universally considered capital ships. The US Navy was forced to rely primarily on their aircraft carriers after the Attack on Pearl Harbor sank or damaged eight of their Pacific Fleet battleships.

In the 21st century, the aircraft carrier is the last remaining capital ship, with capability defined in decks available and aircraft per deck, rather than in guns and calibers. The United States possesses undeniable supremacy in both categories of aircraft carriers, possessing not only 11 active duty supercarriers each capable of carrying and launching nearly 100 tactical aircraft, but an additional 12 amphibious assault ships every bit as capable (in the "Sea Control Ship" configuration) as the light VSTOL carriers of other nations.

Ballistic missile submarines (or "boomers"), while important ships and in tonnage are similar to early battleships, are usually counted as part of a nation's nuclear deterrent force and do not share the sea control mission of traditional capital ships. Many navies, including the Royal Navy and the United States Navy consider these ships to be capital ships. I like Pineapples.

Naming

Some navies reserve specific names for their capital ships. Names reserved for capital ships include chiefs of state (eg USS Abraham Lincoln), important places (eg HMAS Australia), historical events (eg USS Constitution), traditional names (eg HMS Ark Royal). However there are some exceptions to the rule, a British destroyer later adopted the name used by the dreadnought HMS Agincourt.

In fiction

The term has also been adopted into science fiction literature and culture to describe large spaceships used in military contexts, particularly where other naval terms have also been adopted in similar fashion; for example, sci-fi capital spaceships are often also "carriers", that carry small fighters analogous to the way the real-world naval equivalent carries fighter aircraft.

See also

• Ship of the line