Roon-class cruiser

The Roon class was a pair of armored cruisers built for the German Imperial Navy after the turn of the 20th century. The class comprised SMS Roon and SMS Yorck, which closely resembled the earlier ships, but incorporated slight incremental improvements. The ships were easily distinguished from their predecessors by the addition of a fourth funnel. Like all of the armored cruisers built by Germany, they were intended to serve as station ships in Germany's overseas possessions. The ships did not compare well with their British rivals.

The two ships served with the High Seas Fleet in the reconnaissance squadrons after they joined the fleet in 1905–1906. At the outbreak of World War I in 1914, the ships served alongside the more powerful battlecruisers of the I Scouting Group. While returning to port after a raid of the English coast on 16 December 1914, Yorck struck German mines and sank with heavy loss of life. Roon was disarmed in 1916 and intended to be converted into a seaplane carrier, though this was never carried out. The ship was eventually broken up for scrap in 1921.

Design
Design work on Roon and her sister ship Yorck was completed in 1901. The design for the Roon class can be traced back to the first German armored cruiser, SMS Fürst Bismarck (1896), built between 1896–1900, and the preceding of protected cruisers that came before it. The German armored cruisers were designed for overseas service, specifically to serve as station ships in the German colonies in Africa, Asia, and the Pacific.

Roon and her sister Yorck were improved versions of the preceding Prinz Adalbert class. The two ships were slightly larger and faster than the Prinz Adalbert class and had a slightly different armor layout; the Roon class ships had thinner armor on the turret faces, and slightly thinner armored decks. They shared many of the same layout characteristics as the contemporary German pre-dreadnought battleships, including a smaller main armament but heavier secondary battery than their foreign equivalents. As a result, they compared unfavorably with their British contemporaries. Taylor describes the ships as "poorly protected and not a successful class in service."

General characteristics
The ships of the Roon class were 127.3 m long at the waterline and 127.8 m overall. They had a beam of 20.2 m and a draft of 7.76 m. Roon and Yorck displaced 9533 MT normally, and 10266 MT at full load. Their hulls were constructed from transverse and longitudinal steel frames that formed a structure over which the steel hull plates were riveted. The hulls contained 12 watertight compartments and a double bottom that ran for 60 percent of the length of the ship.

Like the preceding Prinz Adalbert-class ships, Roon and Yorck were good sea boats; when the fuel bunkers were full they had a gentle motion. They also maneuvered well and were responsive to the helm. With the rudder hard over, the ships lost up to 60 percent speed. The ships' casemates were placed too low, and as a result they were exceedingly wet; the casemate guns were impossible to use in heavy seas. They had a metacentric height of 1.04 m. The ships' standard complements numbered some 35 officers and 598 enlisted men. While serving as a squadron flagship the crew was augmented by 13 officers and 62 men, and as a second command ship by 9 officers and 44 sailors.

Propulsion
Roon and Yorck were powered by the same engine system as the preceding class, three 3-cylinder vertical triple expansion engines, each of which drove one of the ships' three screws. The central screw was 4.5 m in diameter, and the outer screws were 4.8 m. Steam was provided to the engines by 16 boilers built by Düsseldorf-Ratinger Röhrenkesselfabrik (Dürr). Each boiler had 4 fireboxes apiece for a total of 48. The propulsion system produced 19000 ihp, which delivered a top speed of 21 kn. The ships had four turbo generators, which provided 260 kilowatts at 110 volts. The ships had a single rudder.

Armament
The ships' primary armament consisted of four 21 cm SK L/40 guns mounted in two twin turrets, one fore and one aft. These guns fired a 108 kg armored-piercing shell at a muzzle velocity of 780 m per second, for a maximum range of 12300 m with their original maximum elevation of 16 degrees. The guns were later improved to 30 degrees, which extended the maximum range to 16200 m.

Secondary armament included ten 15 cm SK L/40 guns in single turrets and casemates and fourteen 8.8 cm SK L/35 guns, also casemated. The 15 cm guns fired a 40 kg shell at a muzzle velocity of 800 m per second. The guns could be elevated to 30 degrees, which provided a maximum range of 13900 m. The 8.8 cm guns fired a 7 kg shell at a muzzle velocity of 770 m per second. These guns had a maximum elevation of 25 degrees and a range of 9100 m. The ships were also equipped with four 45 cm torpedo tubes.

This armament was identical to that on the preceding, with the exception of ammunition stores. The Roon-class ships carried 380 shells for the main battery, 1,600 rounds for the 15 cm guns, and 2,100 shells for the 8.8 cm guns. The planned conversion for Roon to a seaplane carrier called for six 15 cm L/45 guns and six 8.8 cm Flak guns, with 2,400 rounds, though this was never carried out.

Armor
Roon and Yorck were protected by Krupp cemented steel armor. At the waterline, their armored belt was 100 mm thick amidships were the ships' vitals were located. This was decreased slightly to 80 mm on either end of the central section of the belt. The belt was backed by 55 mm of teak planking. At the casemate deck the side armor was also 100 mm thick. The armored deck ranged in thickness from 40 - 60 mm and was connected to the belt by sloped armor that was 40 - 50 mm thick.

The forward conning tower had 150 mm thick sides and a 30 mm thick roof. The rear conning tower was less well-protected; its sides were only 80 mm thick and its roof was 20 mm thick. The main battery gun turrets were armored with 150 mm thick steel plates on the sides and 30 mm thick roofs. The 15 cm turrets were protected by 100 mm thick sides and 80 mm thick gun shields.

Construction
Roon was laid down in 1902 at the Kiel Navy dockyard. She was launched on 27 June 1903 and completed on 5 April 1906, at the cost of 15,345,000 marks. Yorck was laid down in February 1903, at Blohm & Voss shipyard. Yorck was launched on 14 May 1904 and completed on 21 November 1905 at a cost of 16,241,000 marks. Roon was laid down as Ersatz Kaiser, as a replacement for the old armored frigate SMS Kaiser (1875), which had been renamed Uranus and used as a harbor ship. Yorck was ordered as Ersatz Deutschland to replace SMS Deutschland (1874), the sistership to Kaiser, which had renamed Jupiter and converted into a target ship.

SMS Roon
After commissioning into the fleet, SMS Roon was assigned to the I Scouting Group. In 1908, she served as the flagship for Rear Admiral Jacobsen in the second division. Roon served here until 1912 when she was replaced by the new battlecruiser SMS Moltke.

At the start of World War I, Roon was serving as the flagship of the III Scouting Group. The ship participated in several actions during World War I, including the raid on Scarborough, Hartlepool and Whitby, during which she served in the cruiser screen for the dreadnoughts of the High Seas Fleet. Roon also conducted operations against Russian forces in the Baltic Sea, including bombardments against the Russian positions at Libau in support of the army in May 1915. The Battle of the Åland Islands took place between Roon and several other German cruisers and Russian forces led by the powerful cruiser Rurik. in July 1915. In August Roon and SMS Prinz Heinrich bombarded Russian positions in the Baltic and briefly engaged several Russian destroyers.

After 1916, Roon was disarmed and used as a guard ship and floating barracks in Kiel until the end of the war. Design work commenced in 1916 to convert the ship into a seaplane carrier; work was planned to last from 1917 to 1918 during a period of 20 months. The ship was struck from the naval register on 25 November 1920 and scrapped the following year at Kiel-Nordmole.

SMS Yorck
SMS Yorck also served in the I Scouting Group with her sister ship, in the second division. In 1908, the ship won the annual "Kaiser's Challenge Cups for Prize Firing" for the reconnaissance squadron. In 1911, the ship came under the command of Franz von Hipper, who would go on to command the I Scouting Group during the war. Hipper held this position aboard Yorck from 1 October 1911 to 26 January 1912. In early 1912 the ship was decommissioned and her crew was transferred to the new battlecruiser SMS Seydlitz.

The ship had a short career during World War I. At the outbreak of war, Yorck was brought out of the reserve fleet and joined her sistership Roon in the III Scouting Group. After the raid on Scarborough, Hartlepool and Whitby, the ship made a navigational error upon returning to the Jadebusen, and accidentally sailed into a German defensive minefield. The ship sank quickly and only 127 men of her complement of 629 were rescued. The wreck was cleared over several periods between 1929 and the mid-1980s. The first period of work lasted from 1929–30; work commenced briefly in 1965. The final work on removing the ship began in 1982.