SMS Posen

SMS Posen was one of four battleships in the Nassau class, the first dreadnoughts built for the German Imperial Navy (Kaiserliche Marine). The ship was laid down at the Germaniawerft shipyard in Kiel on 11 June 1907, launched on 12 December 1908, and commissioned into the High Seas Fleet on 31 May 1910. She was equipped with a main battery of twelve 28 cm (11 in) guns in six twin turrets in an unusual hexagonal arrangement.

The ship served with her three sister ships for the majority of World War I. She saw extensive service in the North Sea, where she took part in several fleet sorties. These culminated in the Battle of Jutland on 31 May – 1 June 1916, where Posen was heavily engaged in night-fighting against British light forces. In the confusion, the ship accidentally rammed the light cruiser SMS Elbing, which suffered serious damage and was scuttled later in the night.

The ship also conducted several deployments to the Baltic Sea against the Russian Navy. In the first of these, Posen supported a German naval assault in the Battle of the Gulf of Riga. The ship was sent back to the Baltic in 1918 to support the White Finns in the Finnish Civil War. At the end of the war, Posen remained in Germany while the majority of the fleet was interned in Scapa Flow. In 1919, following the scuttling of the German fleet in Scapa Flow, she was ceded to the British as a replacement for the ships that had been sunk. She was then sent to ship-breakers in the Netherlands and scrapped in 1922.

Design work on the Nassau class began in late 1903 in the context of the Anglo-German naval arms race; at the time, battleships of foreign navies had begun to carry increasingly heavy secondary batteries, including Italian and American ships with 20.3 cm (8 in) guns and British ships with 23.4 cm (9.2 in) guns, outclassing the previous German battleships of the Deutschland class with their 17 cm (6.7 in) secondaries. German designers initially considered ships equipped with 21 cm (8.3 in) secondary guns, but erroneous reports in early 1904 that the British Lord Nelson-class battleships would be equipped with a secondary battery of as many as ten 25.4 cm (10 in) guns prompted them to consider an even more powerful ship armed with an all-big-gun armament consisting of eight 28 cm (11 in) guns. This initial version was approved in March 1905, but further developments were incorporated over the course of the year, in part due to lessons learned during the on-going Russo-Japanese War. By January 1906, the design was refined into a larger vessel with twelve of the guns, by which time Britain had begun work on the all-big-gun battleship HMS Dreadnought.

Posen was 146.1 m (479 ft) long, 26.9 m (88 ft 3.1 in) wide, and had a draft of 8.9 m (29 ft 2.4 in). She displaced 18,873 metric tons (18,575 long tons) with a standard load, and 20,535 t (20,211 long tons) fully laden. She had a flush deck and a ram bow, a common feature for warships of the period. Posen had a fairly small superstructure, consisting primarily of forward and aft conning towers. She was fitted with a pair of pole masts for signaling and observation purposes. The ship had a crew of 40 officers and 968 enlisted men.

Posen retained 3-shaft triple expansion engines instead of the more advanced turbine engines. Steam was provided to the engines by twelve coal-fired water-tube boilers, which were vented through two funnels. Her propulsion system was rated at 22,000 metric horsepower (22,000 ihp; 16,000 kW) and provided a top speed of 20 knots (37 km/h; 23 mph). She had a cruising radius of 8,300 nautical miles (15,400 km; 9,600 mi) at a speed of 12 knots (22 km/h; 14 mph).

Posen carried a main battery of twelve 28 cm (11 in) SK L/45 guns in six gun turrets arranged in an unusual hexagonal configuration. One was placed forward, another toward the stern, and the remaining four were placed on the wings, two per broadside. Her secondary armament consisted of twelve 15 cm (5.9 in) SK L/45 guns, mounted in casemates located amidships. Close-range defense against torpedo boats was provided by a tertiary battery of sixteen 8.8 cm (3 in) SK L/45 guns, which were also mounted in casemates. Later in her career, two of the 8.8 cm guns were replaced with high-angle Flak mountings of the same caliber for defense against aircraft. The ship was also armed with six 45 cm (17.7 in) submerged torpedo tubes. One tube was mounted in the bow, another in the stern, and two on each broadside, on either ends of the torpedo bulkhead.

The ship's hull was protected by heavy armor plate consisting of Krupp cemented steel. The belt armor along the sides of the hull was 29 cm (11.5 in) thick in the central portion, tapering down to 10 cm (4 in) at the bow. The belt was reinforced by an armored deck that angled downward at the sides to connect to the bottom edge of the belt. The deck was 3.8 cm (1.5 in) on the flat portion, while the sloped sides increased in thickness to 5.8 cm (2.3 in). Posen's main battery turrets had 28 cm of Krupp steel on their faces. Her forward conning tower had 30 cm (11.8 in) of armor plate on the sides, while the aft tower received only 20 cm (7.9 in) on the sides.