Light cruisers

A light cruiser is a type of small- or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck. Prior to this smaller cruisers had been of the protected cruiser model, possessing armored decks only.

The first small steam-powered cruisers were built for the British Royal Navy with HMS Mercury launched in 1878. Such second and third class protected cruisers evolved, gradually becoming faster, better armed and better protected. Germany took a lead in small cruiser design in the 1890s, building a class of fast cruisers—the Gazelle class—copied by other nations. Such vessels were powered by coal-fired boilers and reciprocating steam engines and relied in part on the arrangement of coal bunkers for their protection. The adoption of oil-fired water-tube boilers and steam turbine engines meant that older small cruisers rapidly became obsolete. Furthermore, new construction could not rely on the protection of coal bunkers and would therefore have to adopt some form of side armoring. The British Bristol group of Town-class cruisers (1909) were a departure from previous designs; with turbine propulsion, mixed coal and oil firing and a 2-inch protective armoured belt as well as deck. Thus, by definition, they were armoured cruisers, despite displacing only 4,800 tons; the light armored cruiser had arrived. The first true modern light cruisers were the Arethusa class (1911) which had all oil-firing and used lightweight destroyer-type machinery to make 29 knots (54 km/h).

By World War I, British light cruisers often had either two 6-inch (152 mm) and perhaps eight 4-inch (102 mm) guns, or a uniform armament of 6-inch guns on a ship of around 5,000 tons, while German light cruisers progressed during the war from 4.1-inch (104 mm) to 5.9-inch (150 mm) guns. Cruiser construction in Britain continued uninterrupted until Admiral "Jacky" Fisher's appointment as First Sea Lord in 1904. Due in part to the desire to curtail excess expenditures in light of the increasing cost of keeping up with German naval production and in part because he felt the type to be outdated, Fisher authorized few new cruisers and scrapped 70 older ones. Fisher's belief that battlecruisers would take the place of light cruisers to protect commercial shipping soon proved impractical, as their high construction cost precluded their availability in sufficient numbers to do so, and destroyers were too small for scouting duties. The group of 21 Town-class cruisers begun in 1910 proved excellent in scouting in all types of weather and could carry enough fuel and ammunition to guard the shipping lanes. The Arethusa class, launched three years later, was also successful. British designers continued enlarging and refining subsequent cruiser designs throughout the war.

...
Wikipedia