SMS was a unique German armored cruiser built at the turn of the 20th century for the German (Imperial Navy), named after Kaiser Wilhelm II's younger brother Prince Heinrich. The second vessel of that type built in Germany, was constructed at the (Imperial Shipyard) in Kiel, being laid down in December 1898, launched in March 1900, and commissioned in March 1902. s design was a modification of the previous armored cruiser, , and traded a smaller main battery and thinner armor for higher speed. All subsequent German armored cruisers were incremental developments of .
served with the German fleet in home waters for just four years, from 1902 to 1906, when she was withdrawn from front-line service. During this period, she served as the flagship of the fleet's scouting forces, and she was primarily occupied with fleet training. The ship was out of service from early 1906 to mid-1908, when she was reactivated for use as a gunnery training ship, a role she filled until late 1912. underwent modernization and conversion into a dedicated training ship in 1914, and the work was completed just before the outbreak of World War I in July that year.
After the outbreak of war, the ship was reactivated for active service, initially with III Scouting Group with the High Seas Fleet. was used for coastal defense in the North Sea and she participated in the fleet sortie that supported the Raid on Scarborough, Hartlepool and Whitby in December 1914. After the naval command determined that was too old to serve in the North Sea against the powerful British Royal Navy, she was transferred to the Baltic Sea in early 1915. She supported offensive minelaying operations and patrolled the central Baltic for Russian forces, but never encountered hostile forces. She provided gunfire support during the attack on Libau in May 1915 and shelled Russian positions during the Battle of the Gulf of Riga in August. In the face of severe crew shortages in late 1915, had her crew reduced and was ultimately decommissioned and disarmed in March 1916. She thereafter served in a variety of secondary roles for the rest of the war, before being broken up in 1920.
Design
, the second armored cruiser built in Germany, was authorized under the 1898 Naval Law, the first naval construction program begun under the direction of Alfred von Tirpitz, the State Secretary of the (Imperial Naval Office). The design for was prepared in the late 1890s while construction of the first vessel, , was still underway. Some older naval historians, including Hugh Lyon and John Taylor, writing in 1979 and 1969, respectively, have stated that was intended for overseas service, but Aidan Dodson points out that the ship's hull was not sheathed with wood and copper or zinc layers, which would have been necessary for any ship deployed overseas where shipyard facilities would not be readily available. Dodson also noted that the ship never actually went abroad on an extended deployment.
The design staff based the new vessel on the basic design of , but for budgetary reasons the new ship's size was reduced by about . Weight reduction was achieved in part by thinning the ship's armor layout, though advances in steel technology meant this was not actually a compromise and her armor layout was in fact significantly more effective than s. Krupp had recently developed cemented armor plate, which was considerably stronger than earlier Harvey armor, so less of it could be used to achieve the same level of protection. In addition, the belt could be made taller, extending up to the main deck level, which protected more of the ship's interior. The ship's deck armor sloped down on the sides, where it was connected to the lower edge of the belt, which considerably strengthened the protection system by providing another layer of armor that would need to be penetrated before the ship's vitals could be damaged.
The armament was also significantly reduced to save weight and cost, from four heavy guns in two twin-gun turrets to two guns, each in single turrets; she also received two fewer secondary guns compared to . But rather than spreading the secondary battery along the length of the hull in casemates and sponsons, they were concentrated in a battery amidships, which reduced the amount of the hull that needed to be protected with armor, further saving weight and allowing thicker armor to be concentrated in the battery. Further weight savings were achieved by adopting a smaller superstructure and discarding heavy military masts in favor of lighter pole masts. Her engines, however, were some more powerful, which produced a faster vessel.