The Scharnhorst class was the last class of traditional armored cruisers built by the German Kaiserliche Marine (Imperial Navy). The class comprised two ships, Scharnhorst and Gneisenau. They were larger than the Roon-class cruisers that preceded them; the extra size was used primarily to increase the main armament of 21 cm (8.2 inch) guns from four to eight. The ships were the first German cruisers to reach equality with their British counterparts. The ships were named after 19th century Prussian army reformers, Gerhard von Scharnhorst and August von Gneisenau.

Built for overseas service, Scharnhorst and Gneisenau were assigned to the East Asia Squadron in 1909 and 1910, respectively. Scharnhorst relieved the old armored cruiser Fürst Bismarck as the squadron flagship, which had been on station since 1900. Both ships had short careers; shortly before the outbreak of World War I, the ships departed the German colony at Qingdao. On 1 November 1914, the ships destroyed a British force at the Battle of Coronel and inflicted upon the Royal Navy its first defeat since the Battle of Plattsburgh in 1814. The East Asia Squadron, including both Scharnhorst-class ships, was subsequently annihilated at the Battle of the Falkland Islands on 8 December.

The Second Naval Law in Germany, passed in 1900, envisioned a force of fourteen armored cruisers for both service overseas in Germany's colonial empire and as scouts for the main battle fleet in German waters. The naval expansion program was primarily directed against the British Royal Navy, then the world's preeminent naval force. Germany's armored cruiser force followed a series of iterative developments based on the cruiser Prinz Heinrich, and the Scharnhorst class represented the culmination of that evolutionary development.

During the design process for the class, the General Department issued a request that the new cruisers be capable of fighting in the line of battle in the event that German battleships were damaged and unable to continue fighting. Up to this point, this had not been a consideration in German armored cruiser construction, and so a significant increase in both firepower and armor protection would be required to accommodate it. This in turn required much larger ships, and the Scharnhorsts were accordingly about 2,000 t (1,970 long tons; 2,200 short tons) heavier than the preceding Roons. The weight increase secured a doubling of the main battery, a 50% increase in belt armor, and an increase in top speed by more than a knot over the Roon class. The speed increase was achieved by the addition of two boilers that provided 7,100 metric horsepower (7,000 ihp) more power for the propulsion system. As a result of these improvements, the Scharnhorst class was the first German armored cruiser design that compared favorably to its foreign counterparts.

Several other minor changes were introduced, including a strengthening of the tertiary battery of 8.8 cm (3.5 in) guns to the level used in contemporary battleships like the Deutschland class. The design staff considered adding a pair of these guns to the conning tower roof abreast of the bridge, but experience with the same arrangement on the Braunschweig-class battleships demonstrated the excessive blast effect interfered with control of the ships, and so those guns were suppressed in the Scharnhorst design.

The ships of the class were 144.60 meters (474 ft 5 in) long overall, and 143.80 m (471 ft 9 in) long at the waterline. They had a beam of 21.60 m (70 ft 10 in), a draft of 8.37 m (27 ft 6 in), and displaced 11,616 t (11,433 long tons; 12,804 short tons) standard, and 12,985 t (12,780 long tons; 14,314 short tons) at full load. The ships' hulls were constructed of transverse and longitudinal steel frames, over which the outer hull plating was riveted. The vessels had 15 watertight compartments and a double bottom that ran for 50% of the length of the hull.

The ships had a standard crew of 38 officers and 726 enlisted men. Scharnhorst, as the squadron flagship, had a larger crew, including an additional 14 officers and 62 men. Gneisenau, when serving as the squadron second command flagship, had an extra staff of 3 officers and 25 men. The ships carried a number of smaller vessels, including two picket boats, two launches, one pinnace, two cutters, three yawls, and one dinghy.

The Scharnhorst-class ships used the same powerplant as in the preceding Roon class: three 3-cylinder triple expansion engines. Each engine drove a single propeller; that one the center shaft on Scharnhorst was 4.7 m (15 ft 5 in) in diameter while the outer two were 5 m (16 ft 5 in) wide. Gneisenau's screws were slightly smaller, at 4.60 m (15 ft 1 in) wide on the center shaft and 4.80 m (15 ft 9 in) on the outer pair. The triple expansion engines were supplied with steam by 18 coal-fired marine-type boilers with 36 fire boxes. The engines were designed to provide 26,000 metric horsepower (19,000 kW; 26,000 ihp), though on trials they achieved higher figures—28,782 ihp for Scharnhorst and 30,396 ihp for Gneisenau. The ships were rated at a top speed of 22.5 knots (41.7 km/h; 25.9 mph), though on trials Scharnhorst steamed at a maximum of 23.5 knots (43.5 km/h; 27.0 mph), while Gneisenau ran at 23.6 knots (43.7 km/h; 27.2 mph). The vessels carried 800 t (790 long tons; 880 short tons) of coal normally, though they were capable of storing up to 2,000 t (2,000 long tons; 2,200 short tons) of coal. This provided a maximum range of 4,800 nautical miles (8,900 km; 5,500 mi) at a cruising speed of 14 knots (26 km/h; 16 mph). The ships had a single rudder. The vessels' electrical plant consisted of four turbo-generators that delivered 260 kilowatts at 110 volts.

The ships' main battery armament consisted of eight 21 cm (8.3 in) SK L/40 guns, four in twin gun turrets, one fore and one aft of the main superstructure on the centerline, and the remaining four were mounted in single casemates located amidships. The turrets were the DrL C/01 type, which was hydraulically operated, and the mounts provided a range of elevation from -5 to +30 degrees. The casemates used electric motors to train the guns, but elevation was hand-operated. These guns fired a 108-kilogram (238 lb) armor-piercing shell at a muzzle velocity of 780 meters per second (2,600 ft/s). The turrets had a maximum range of 16,200 m (53,100 ft), while the casemates could only engage targets out to 12,300 m (13,500 yd). The guns were supplied with a total of 700 rounds.

The secondary armament included six 15 cm (5.9 in) SK L/40 guns in individual casemates. These guns fired a 40 kg (88 lb) shell at a muzzle velocity of 800 m/s (2,600 ft/s). They could be elevated to 30 degrees, which provided a maximum range of 13,900 m (15,200 yd). For close-range defense against torpedo boats, the ships carried a tertiary battery of eighteen 8.8 cm SK L/35 guns, which were mounted in individual casemates and pivot mounts in the superstructure. The 8.8 cm guns fired a 7 kg (15 lb) shell at a muzzle velocity of 770 m/s (2,500 ft/s). These guns had a maximum elevation of 25 degrees and a range of 9,100 m (10,000 yd).

As was customary for warships of the period, the Scharnhorst-class ships were equipped with four 45 cm (18 in) submerged torpedo tubes. One was mounted in the bow, one on each broadside, and the fourth was placed in the stern. The ships were supplied with a total of 11 torpedoes. The C/03 torpedo carried a 147.5-kilogram (325 lb) warhead and had a range of 1,500 m (4,900 ft) when set at a speed of 31 knots (57 km/h; 36 mph) and 3,000 m (9,800 ft) at 26 knots (48 km/h; 30 mph).

As was the standard for German warships, the ships of the Scharnhorst class were protected by Krupp armor. They had an armor belt that was 150 mm (5.9 in) thick in the central portion of the ship, extending from abreast the forward conning tower to just aft of the rear tower, where the propulsion machinery areas were located. This was a significant increase in thickness over earlier German armored cruisers. Tests at the navy's firing range at Meppen had revealed that the 100 mm (3.9 in) belt used in all preceding designs was too thin to stop the medium-caliber shells that the cruisers would likely face in combat. The belt decreased to 80 mm (3.1 in) on either end of the central citadel; this extended all the way to the bow and almost completely to the stern, the extreme end of which was not armored. The entire belt was backed with teak planking. The main armored deck ranged in thickness from 60 mm (2.4 in) over critical areas and down to 35 mm (1.4 in) elsewhere. The deck sloped down to connect to the belt at its lower edge; this portion was between 40–55 mm (1.6–2.2 in) thick.

The forward conning tower had 200 mm (7.9 in) thick sides and a 30 mm (1.2 in) thick roof. The rear conning tower was less well-armored, with sides that were only 50 mm (2.0 in) thick and a roof that was 20 mm (0.79 in) thick. The main battery gun turrets had 170 mm (6.7 in) thick sides and 30 mm (1.2 in) thick roofs, while the amidships guns were protected with 150 mm (5.9 in) thick gun shields and 40 mm (1.6 in) thick roofs. The barbettes that supported the turrets were 140 mm (5.5 in) thick. The 15 cm battery was protected by a strake of armor that was 130 mm (5.1 in) thick, while the guns themselves were protected with 80 mm (3.1 in) thick shields.

Construction data

Name	Builder	Namesake	Laid down	Launched	Commissioned
Scharnhorst	Blohm & Voss, Hamburg	Gerhard von Scharnhorst	22 March 1905	23 March 1906	24 October 1907
Gneisenau	AG Weser, Bremen	August Neidhardt von Gneisenau	28 December 1904	14 June 1906	6 March 1908

Upon commissioning, both ships of the class were assigned to the East Asia Squadron, with Scharnhorst serving as Admiral Maximilian von Spee's flagship. Scharnhorst and Gneisenau were regarded as well-trained vessels; both ships won awards for their excellence at gunnery. At the start of World War I, the two ships were in the Caroline Islands on a routine cruise; the rest of Spee's squadron was dispersed around the Pacific. The declaration of war by Japan on Germany convinced Spee to consolidate his force with the cruisers Leipzig and Dresden from the American station, and head for Chile to refuel. The flotilla would then attempt to return to Germany via the Atlantic Ocean. Spee also intended to attack the three British cruisers under the command of Admiral Christopher Cradock, and any British shipping encountered. On 22 September, Scharnhorst and Gneisenau approached the island of Papeete in French Polynesia with the intention of seizing the coal stockpiled in the harbor. The ships conducted a short bombardment that resulted in the sinking of the old gunboat Zélée. However, Spee feared that the harbor had been mined, and decided to avoid the risk. The French had also set fire to the coal stocks to prevent the Germans from using the coal.

At approximately 17:00 on 1 November 1914, the East Asia Squadron encountered Cradock's ships off Coronel. Because the German ships had an advantage in speed, Spee was able to keep the distance to 18 kilometers, before closing to 12 km (6.5 nmi) to engage the British flotilla at 19:00. Scharnhorst hit Good Hope some 34 times; at least one of the shells penetrated Good Hope's ammunition magazines, which resulted in a tremendous explosion that destroyed the ship. The light cruiser Nürnberg closed to point-blank range to attack Monmouth; after a severe pummeling, Monmouth sank as well. The British light cruiser Glasgow and the auxiliary cruiser Otranto both escaped under the cover of darkness. First Sea Lord Jackie Fisher remarked that it was "the saddest naval action of the war." The defeat was the first to be inflicted on the Royal Navy since the 1814 Battle of Plattsburgh. After news of the battle reached Kaiser Wilhelm II in Berlin, he ordered 300 Iron Crosses to be awarded to the men of Spee's squadron. After refueling in Valparaiso, the East Asia Squadron departed for the Falkland Islands, in order to destroy the British wireless transmitter located there.

Some six hours after news of the battle reached England, Fisher ordered Admiral John Jellicoe, the commander of the Grand Fleet, to detach the battlecruisers Invincible and Inflexible to hunt down the German ships. Vice Admiral Doveton Sturdee was placed in command of the flotilla, which also included the armored cruisers Carnarvon, Cornwall, Defence, and Kent, and the light cruisers Bristol and Glasgow, which had survived Coronel. Sturdee's ships reached the Falklands by the morning of 8 December, shortly before Spee's squadron arrived. The British spotted the East Asia Squadron at 09:40; Spee was unaware that the British had sent the two battlecruisers, and when he observed them, he ordered his ships to withdraw. Despite the head start, the fast battlecruisers quickly caught up with the worn-out German ships, which had just completed a 16,000 mile voyage without repairs.

At approximately 13:20, the battlecruisers opened fire at a range of 14 kilometers (8.7 mi). After a two-hour-long battle, Scharnhorst was dead in the water and listing heavily. The ship was sunk shortly thereafter. Gneisenau had been hit more than 50 times at close range; the crew gave three cheers for the Kaiser before the vessel sank. Nürnberg and Leipzig were also sunk, though Dresden managed to escape temporarily, before she too was destroyed off Juan Fernández Island. Some 2,200 men were killed, among them Spee.

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