SMS Schleswig-Holstein[a] (pronounced [ˌʃleːsvɪç ˈhɔlʃtaɪn] ⓘ) was the last of the five pre-dreadnought Deutschland-class battleships built by the German Kaiserliche Marine.

The ship, named for the province of Schleswig-Holstein, was laid down in the Germaniawerft dockyard in Kiel in August 1905 and commissioned into the fleet nearly three years later.

The ships of her class were already outdated by the time they entered service, being inferior in size, armor, firepower and speed to the new generation of dreadnought battleships.

Schleswig-Holstein fired the first cannon shots of World War II when she bombarded the Polish base at Danzig's Westerplatte in the early morning hours of 1 September 1939.

The passage of the Second Naval Law in 1900 under the direction of Vizeadmiral (VAdm—Vice Admiral) Alfred von Tirpitz secured funding for the construction of twenty new battleships over the next seventeen years.

She was equipped with three triple expansion engines and twelve coal-fired water-tube boilers that produced a rated 16,767 indicated horsepower (12,503 kW) and a top speed of 19.1 knots (35.4 km/h; 22.0 mph).

[9] On 14 July 1914, the annual summer cruise to Norway began, but the threat of war in Europe cut the excursion short; within two weeks Schleswig-Holstein and the rest of II Squadron had returned to Wilhelmshaven.

[11] At the outbreak of war in July 1914, Schleswig-Holstein was assigned to guard duty in the mouth of the Elbe River while the rest of the fleet mobilized.

[1] In late October, she and her sisters were sent to Kiel to have improvements made to their underwater protection system to make them more resistant to torpedoes and mines,[10] after which II Battle Squadron rejoined the fleet.

The squadron covered Rear Admiral Franz von Hipper's battlecruisers of the I Scouting Group while they bombarded Scarborough, Hartlepool, and Whitby on 15–16 December 1914.

[1] During the operation, the German battle fleet of some 12 dreadnoughts and 8 pre-dreadnoughts came to within 10 nmi (19 km; 12 mi) of an isolated squadron of six British battleships.

[16] During the "Run to the North", Scheer ordered the fleet to pursue the retreating battleships of the British 5th Battle Squadron at top speed.

[20] Admiral Scheer decided to reverse the course of the fleet with the Gefechtskehrtwendung, a maneuver that required every unit in the German line to turn 180° simultaneously.

[21][c] Having fallen behind, the ships of II Battle Squadron could not conform to the new course following the turn,[23] and fell to the disengaged side of the German line.

Admiral Mauve considered moving his ships to the rear of the line, astern of III Battle Squadron dreadnoughts, but decided against it when he realized the movement would interfere with the maneuvering of Hipper's battlecruisers.

[24] But by the time II Squadron reached its position at the head of the line, Scheer had ordered another Gefechtskehrtwendung, which placed them at the rear of the German fleet.

At 21:35 a heavy caliber shell struck the ship on the port-side,[27][e] punching a hole approximately 40 cm (16 in) wide before exploding against the inner casemate armor.

[32] Late on the 31st, the fleet re-formed for the night voyage back to Germany, with Schleswig-Holstein towards the rear of the line, ahead of Hessen, Hannover, and the battlecruisers Von der Tann and Derfflinger.

[36] Despite the ferocity of the night fighting, the High Seas Fleet punched through the British destroyer forces and reached Horns Reef by 4:00 on 1 June.

[37] The German fleet reached Wilhelmshaven a few hours later, where the undamaged dreadnoughts of the Nassau and Helgoland classes took up defensive positions.

[1] The Navy then decided to withdraw the four remaining Deutschland-class ships, owing to their obsolescence and vulnerability to underwater attacks, as demonstrated by the loss of Pommern.

[42] Schleswig-Holstein was recommissioned as the new fleet flagship on 31 January 1926 following an extensive refit, with new fire controls and an enlarged aft superstructure for the admiral's staff.

The crew was supplemented by 175 cadets,[47] who were taken on long cruises in Schlesien and Schleswig-Holstein, the latter sailing in October 1936 on a six-month voyage to South America and the Caribbean.

[12] In the mid-1930s, Hitler began pursuing an increasingly aggressive foreign policy; in 1936 he re-militarized the Rhineland, and in 1938 completed the Anschluss of Austria and the annexation of the Sudetenland.

Schleswig-Holstein had been positioned in the port of Danzig, moored close to the Polish ammunition depot at Westerplatte under the guise of a ceremonial visit in August.

[55] A force of German infantry and army engineers went ashore to take the depot, with heavy fire support from Schleswig-Holstein.

Along with the torpedo boat Claus von Bevern and several auxiliary ships, her objective was to support the capture of Korsør and Nyborg.

She was to be converted into a convoy escort ship with a greatly enhanced anti-aircraft armament, but after being hit three times by Royal Air Force bombers on 18 December 1944, she eventually foundered in shallow water.

Although reference books long stated that she was scrapped there or in Marienburg,[64][66] in actuality she was towed out in 1948 and beached for long-term use as a target in shallow water off the island of Osmussaar in the Gulf of Finland.