The battlecruiser 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 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 development of the armoured cruiser, at the same time as the dreadnought succeeded the pre-dreadnought battleship. The goal of the design 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.
HMS Hood, the largest battlecruiser ever built, in Australia on 17 March 1924
HMS Shannon, a Minotaur-class armoured cruiser
Invincible, Britain's first battlecruiser
HMS Queen Mary, the last battlecruiser built before World War I
The capital ships of a navy are its most important warships; they are generally the larger ships when compared to other warships in their respective fleet. A capital ship is generally a leading or a primary ship in a naval fleet.
Aircraft carriers form the main capital ships of most modern-era blue-water navies.
Battleships became the main form of capital ship after sailing vessels fell out of use, and remained so up to World War II. Shown is the German SMS Helgoland.
Ships of the line (of battle) were the capital ships of the era of sail. Pictured is the Spanish Santa Ana, a very large example with 112 guns.
British battlecruiser HMS Repulse