The class of armored corvettes was a class of four ships built by the Imperial German Navy in the late 1870s to early 1880s. The ships—, , , and —were designed to operate as part of an integrated coastal defense network. The ships were intended to sortie from fortified bases to break up an enemy blockade or landing attempt. Armed with six guns, they were also intended to fight hostile ironclads on relatively equal terms.
Following their commissionings in 1878–1883, the four ships served with the fleet on numerous training exercises and cruises in the 1880s and 1890s. They also participated in several cruises escorting Kaiser Wilhelm II on state visits to Great Britain and to various cities in the Baltic Sea in the late 1880s and early 1890s. In the late 1890s, the four ships were extensively rebuilt; their secondary batteries were modernized and they received upgraded propulsion systems. They were removed from active duty between 1902 and 1910 and relegated to secondary duties. and became target ships while became a torpedo training ship. The three ships were broken up for scrap in 1919–1920. was used as a boom defense hulk from 1910 to 1920, when she became a target ship. She survived until 1938, when she was sold for scrapping.
Background
The origin of the class of ironclad corvettes traces back to the fleet plan of 1861 approved for the Prussian Navy. The plan called for the construction of four small ironclads that had a shallow-enough draft to allow them to operate in the Baltic Sea, where larger armored frigates would be unable to maneuver. These ships were never built, owing to a combination of budgetary limitations, technical inexperience in Prussian shipyards, and other factors. But the blockade the Danish Navy had imposed during the Second Schleswig War of 1864 and the operations of the French fleet during the Franco-Prussian War of 1870–1871 made clear the vulnerability of the long Baltic coastline to enemy attacks. After the Franco-Prussian war, General Albrecht von Stosch became the Chief of the Imperial Admiralty; he immediately set about drafting a new fleet plan, based on the most recent program that had been approved in 1867.
Stosch saw the role of the navy as primarily defensive; a fleet of ironclad warships would be kept in German waters to defend the coast. Stosch's fleet plan, finalized in 1873, called for a total of eight ocean-going ironclads and six smaller, armored corvettes. The quota for sea-going vessels was met by the , while only one armored corvette had been laid down by that point: . The new corvettes were to be the first vessels built under the Imperial government.
The new ships were intended to operate in the Baltic Sea as a primary component of an integrated coastal defense system proposed by Stosch. He designated the ships (sortie corvettes), denoting their intended use. In the event of war with a superior naval power and the imposition of a naval blockade, the -class ships would sortie from fortified bases to attack the blockaders. They also had the task of breaking up landing attempts. The German railway network linked the bases so ground forces could be transferred to the sites of enemy landings. Stosch envisioned using the smaller of armored gunboats to support them, though these proved to be disappointments in service.
Design
Stosch had instructed the design staff to begin work on the next corvette already in 1872, before they had been authorized under the 1873 fleet plan. Work on what became the class continued into 1874. Their roles imposed several design limitations on the vessels. The vessels were designed to operate in coastal areas, which required a shallow draft in order for them to be able to enter any port on the Baltic seaboard. They also required a heavy armament and think armor plate, in order for them to be able to engage any hostile ironclad on equal terms. Because Stosch envisioned only local deployments for the vessels, they did not need a high top speed or a long cruising radius. As a result, they had limited coal stowage, as they would operate close to their bases and could easily replenish fuel. A supplemental sailing rig was rejected for the same reason. Initially, guns were considered, but the design staff decided to use lighter guns instead. The designers adopted the basic format of the British breastwork monitors, but rather than employing the heavy gun turrets used in those vessels, the Germans opted for lighter open barbette mountings.