Light cruiser
While lighter and smaller than other contemporary ships they were still true cruisers, retaining the extended radius of action and self-sufficiency to act independently around the world.
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.
The British Chatham group of Town-class cruisers were a departure from previous designs; with turbine propulsion, mixed coal and oil firing and a 2-inch protective armored belt as well as deck.
The first true modern light cruisers were the Arethusa class which had all oil-firing and used lightweight destroyer-type machinery to make 29 knots (54 km/h).
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.
Compared to the British "scout" type the German ships were bigger, slower and less manoeuvrable but, through a successive series of classes, improved consistently in seagoing qualities.
For about a three-year period after the British Weymouth class of the Town series, completed with a uniform armament of 6-inch guns, and before the German Pillau class, German light cruisers (such as the Magdeburg and Karlsruhe-class cruisers) were faster but maintained a lighter 104 mm main armament compared to their British Town-class counterparts.
The Atlantas and Didos were born out of the tactical need for vessels to protect aircraft carriers, battleships and convoys from air attack.
They traded a main gun turret for additional AA, fire control, and radar installations, over the Brooklyn class.
Similar ships include the protected cruisers Aurora (St. Petersburg) and USS Olympia (Philadelphia, Pennsylvania), and the bow of Puglia (Gardone Riviera).
