The class consisted of five pre-dreadnought battleships of the Imperial German Navy; all ships of the class were named for German emperors. The ships were , , , , and , all built between 1895 and 1901. The class saw the introduction of the traditional armament layout for German battleships prior to the advent of the dreadnought type of battleship in the early 1900s: four large-caliber guns, but of comparatively smaller size compared to their contemporaries, in two gun turrets. The German adoption of smaller guns was a result of a preference for higher volumes of fire over weight of shell. The class also standardized the use of three screws for battleships and introduced water-tube boilers and Krupp cemented armor.
On entering service, the ships were assigned to I Squadron, of which served as the flagship, while served as the flagship for the overall fleet commander. The ships conducted routine training exercises and cruises in the early 1900s and was badly damaged in a grounding accident while steaming in the Baltic Sea in 1901. As newer battleships entered service later in the decade, the ships of the class were moved to II Squadron in 1905 and all of the ships except were rebuilt between 1907 and 1910. Thereafter they were reduced to reserve status beginning in 1908, since more powerful dreadnought battleships had begun to be commissioned; the rest of their peacetime careers consisted of periodic reactivations to participate in annual fleet training maneuvers.
At the start of World War I in July 1914, the ships were recommissioned and assigned to V Squadron; they were tasked with coastal defense in the North Sea but were quickly transferred to the Baltic to support German operations against the Russian Empire. They saw limited activity during this period, and they returned to the North Sea for guard duties in early 1915. The increasing threat of modern weapons, particularly the British submarines that had begun to operate in the area, combined with shortages of crews for more valuable vessels, led the navy to decommission all five members of the class in March 1915. They were used in a variety of secondary roles. They were all discarded in the early 1920s as Germany disarmed under the terms of the Treaty of Versailles.
Design
In the early 1890s, the German Navy attempted to secure funding from the to replace the elderly ironclad , but parliamentary resistance delayed the appropriation until the 1894/1895 budget year. Design studies for the new ship had begun in June 1891 at the request of Kaiser Wilhelm II, and it was quickly decided to make significant changes from the preceding design. The limitations of the fleet's infrastructure, particularly the dry docks and other harbor facilities, along with the Kaiser Wilhelm Canal then under construction, constrained the size of the new ship. To keep the new ship within the displacement limit, the center turret that had been used on the s would have to be sacrificed if a heavier secondary battery was to be incorporated. Five different design sketches were prepared, the first four incorporating a secondary armament of ten guns and eight guns and the fifth replacing the 10.5 cm guns with eight guns. All five variants carried a main armament of four guns. Wilhelm II contributed his own proposal, but it suffered from serious stability problems and was not a serious option.
Work continued on the ships' design while the navy pushed for funding in the , which was finally approved in March 1894, placing pressure on the design staff to complete their work so construction could begin. By May, the design staff had produced sketch XVI, which discarded the traditional two-gun turret used by most navies in favor of four single-gun turrets in the lozenge arrangement used in contemporary French battleships like . If weight permitted, all four were to be 28 cm guns, but the option to reduce the wing turrets to was available if necessary. The secondary battery was to be sixteen of the 10.5 cm guns, with at least some in twin turrets, but over the following months the battery was increased to 15 cm guns, as it was the accepted view at the time that secondary guns would do the most damage in a close-range fight. This view, which advocated the so-called "hail of fire" principle, was seemingly vindicated by the Japanese cruisers' victory over a more heavily-armed Chinese fleet at the Battle of Yalu later in 1894. The smaller, faster-firing guns were intended to inflict serious damage on the superstructures of enemy battleships and demoralize the crew.