Protected cruiser
The frigates and sloops which performed the missions of scouting, commerce raiding and trade protection remained unarmoured.
For several decades, it proved difficult to design a ship which had a meaningful amount of effective armour but at the same time maintained the speed and range required of a "cruising warship".
Ordered in 1880 as modified Iris-class dispatch vessels and re-rated as second-class cruisers before completion, these ships combined an amidships protective armoured deck with the size, lean form and high performance of HMS Mercury.
Leander and her three sisters were successful and established a basis for future Royal Navy cruiser development, through the rest of the century and beyond.
In the case of the latter, the armoured deck was of sufficient thickness to defend against small-calibre guns capable of tracking such a difficult, fast target.
This was very much the philosophy adopted by George Wightwick Rendel in his design of the so-called 'Rendel cruisers' Arturo Prat, Chaoyong and Yangwei.
By enlarging the flatiron gunboat concept, increasing engine power and thus speed, Rendel was able to produce a fast small vessel and still have enough tonnage to incorporate a very thin (one-quarter-inch, 6.4 mm thick) partial protective deck over the machinery.
Still small and relatively weakly built, these vessels were 'proto-protected cruisers' which served as the inspiration for a significantly larger ship; Esmeralda.
The Jeune École school of thought, which proposed a navy composed of fast cruisers for commerce raiding and torpedo boats for coastal defence, became particularly influential in France.
Their primary role, as with the earlier Shannon and Nelsons, was still to function as small battleships on foreign stations, countering enemy stationnaire ironclads rather than chasing down swift commerce-raiding corsairs.
They were conceived as 'fleet torpedo cruisers' to carry out attacks on the enemy battle line and featured heavy guns fore and aft with excellent fields of fire.
Thus, the British notion of the protected cruising warship was being shaped early on by the commercial export models coming out of Elswick.
(For the following decade, practically any British cruiser which was seen to have eschewed very heavy firepower in favour of conservative design balance was subject to fierce public criticism, and this period coincided somewhat unfortunately with Sir William White's tenure as DNC.)
The majority of pre-existing protected cruisers – products of the Victorian-era design generation – had now become obsolete: With their by-now old and worn engines degrading their already-eclipsed performance by this point; their older models of lower-velocity guns able to shoot accurately to a shorter distance than newer equivalent ships, in a period where long-range fire control was a rapidly-developing discipline with technology to match; and finally – most critically – being less well protected than the new generation of side-armoured ships.
The Royal Navy rated cruisers as first, second and third class between the late 1880s and 1905, and built large numbers of them for trade protection requirements.
The smaller cruisers unable to bear the weight of heavy armoured belts retained the "protected" scheme up to 1905, when the last units of the Challenger and Highflyer classes were completed.
The French Navy built and operated a large variety of protected cruisers classes starting with Sfax in 1882.
The German Imperial Navy (Kaiserliche Marine) built a series of protected cruisers in the 1880s and 1890s, starting with the two ships of the Irene class in the 1880s.
[10] Several of the ships served with the German East Asia Squadron, and Hertha, Irene, and Hansa took part in the Battle of Taku Forts in 1900 during the Boxer Rebellion.
[12] Long since obsolete by the outbreak of World War I, the five Victoria Louise-class vessels briefly served as training ships in the Baltic but were withdrawn by the end of 1914 for secondary duties.
The first five ships, Giovanni Bausan and the Etna class, were built as "battleship destroyers", armed with a pair of large caliber guns.
Most of these ships saw action during the Italo-Turkish War of 1911–1912, where several of them supported Italian troops fighting in Libya, and another group operated in the Red Sea.
Most of the earlier cruisers were obsolescent by the outbreak of World War I, and so had either been sold for scrap or reduced to subsidiary roles.
The most modern vessels, including Quarto and the Nino Bixio class, saw limited action in the Adriatic Sea after Italy entered the war in 1915.
