In the days of sailing navies a ship, usually a fourth-rate or large frigate, detached from a fleet to cruise independently in search of the enemy. Frigates and smaller warships engaged in the protection of trade or in the guerre de course were also usually known as cruisers. The one essential characteristic of any ship detached for duty as a cruiser was a good sailing speed, superior to that of any enemy she might encounter.
With the introduction of steam propulsion and iron armour in the mid-19th century, the cruiser gradually became a generic type of warship in its own right. It was built in three or four categories, ranging from armoured cruisers which were large ships of up to 15,000–16,000 tons displacement, through belted cruisers (those protected only by a waterline belt of armour), second-class cruisers with only light armour, and light cruisers with virtually no armour but with a particularly high speed.
The Washington Naval Limitation Treaty of 1922 limited the cruiser to 10,000 tons and classified those with guns of 7.1 in. (17.7 cm) or larger as ‘heavy’ and those with 6 in. (15 cm) or smaller as ‘light’. Virtually all subsequent cruisers carried either 6-in. (15-cm) or 8-in. (20-cm) guns, though the anti-aircraft cruisers built by the Royal Navy during the Second World War (1939–45) for convoy protection were armed with 5.5-in. (13.7-cm) dual purpose guns. The three diesel-engined German pocket battleships Deutschland (later renamed Lützow), Admiral Graf Spee, and Admiral Scheer, with their six 11-in. (27.5-cm) guns and eight 5.7-in. (14.2-cm) guns, were in fact heavily armoured cruisers of 10,000 tons displacement.
The US Navy launched the last all-gun heavy cruiser, Salem, in 1947, but the advent of guided missiles rendered ‘heavy’ and ‘light’ designations for cruisers irrelevant; and, with larger and larger destroyers being built, the difference between the two types of warship has virtually disappeared. No cruisers are built today though the US Navy continues to consider designs for them. See also belfast; warfare at sea.
Subjects: Maritime History.