The class was a group of five heavy cruisers built by Nazi Germany's beginning in the mid-1930s. The class comprised , the lead ship, , , , and . Only the first three ships of the class saw action with the German Navy during World War II. Work on stopped when she was approximately 95 percent complete; it was decided to convert her into an aircraft carrier, but this was not completed either. was sold incomplete to the Soviet Union in 1940.

and took part in Operation Weserübung, the invasion of Norway in April 1940. was sunk by Norwegian coastal defenses outside Oslo while led the attack on Trondheim. She then conducted sorties into the Atlantic to attack Allied merchant shipping. In 1942, she was deployed to northern Norway to attack shipping to the Soviet Union, culminating in the Battle of the Barents Sea in December 1942, where she was damaged by British cruisers. saw her first action during Operation Rheinübung with the battleship . She eventually returned to Germany during the Channel Dash in 1942, after which she too went to Norway. After being torpedoed by a British submarine, she returned to Germany for repairs. , while decommissioned after returning to Germany in early 1943, was partially repaired and recommissioned in the fall of 1944 for a refugee transport mission in 1945. Only continued to serve in full commission and stayed in the Baltic until the end of the war.

was scuttled in Kiel in May 1945, leaving as the only member of the class to survive the war. She was ceded to the United States Navy, which ultimately expended the ship in the Operation Crossroads nuclear tests in 1946. was towed to Königsberg and scuttled before the advancing Soviet Army could seize the ship. She was ultimately raised and broken up for scrap. , renamed , remained unfinished when the Germans invaded the Soviet Union. The ship provided artillery support against advancing German forces until she was sunk in September 1941. She was raised a year later and repaired enough to participate in the campaign to relieve the Siege of Leningrad in 1944. She served on in secondary roles until the 1950s, when she was broken up.

Design

Development Article 181 of the Treaty of Versailles limited the post-war German navy—the —to six battleships of the " or types" and six old light cruisers. These obsolete ships could not be replaced until they were at least twenty years old, and their replacements could displace no more than and , respectively. In February 1922, the major naval powers signed the Washington Naval Treaty; Germany was not invited to attend, but she would be held to the same qualitative limitations as the signatories. By the early 1920s, the cruisers of the were old enough to permit replacement; , the three s, and the two s were built later in the decade to replace the older vessels.

The 1930 London Naval Treaty formally divided cruiser types into two categories: heavy cruisers, armed with guns, and light cruisers, armed with guns. The Treaty of Versailles still prohibited Germany from building heavy cruisers, but the rise of Adolf Hitler's Nazi Party to power in 1933 led to the formal rejection of the Treaty of Versailles. After pulling out of the Geneva Conference in 1933, Hitler argued that if the other European powers did not disarm to parity with Germany, they should accept German rearmament. The German navy, renamed the on 21 May 1935, was now free to pursue rearmament. Germany concluded the Anglo-German Naval Agreement with Great Britain, which set German naval strength at 35% of the size of the Royal Navy. This permitted Germany to build of heavy cruisers, enough for five 10,000-ton ships.

The design for the first three of the five -class ships was prepared in 1934–1935. and were initially designed as light cruisers; their design was prepared in 1934–1936. These last two ships were to be armed with four triple turrets housing guns, as opposed to the four twin 20.3 cm guns on the first three ships. The "light cruisers" were otherwise planned to follow the same particulars as their three "heavy" half-sisters. On 14 November 1936, the Navy decided to complete the final two ships identically to the other members of the class.

General characteristics

The ships of the class varied slightly in size. was long at the waterline and overall. After the installation of a clipper bow during fitting out, her overall length increased to . The ship had a beam of . was long at the waterline and overall; with the clipper bow, her overall length was . Her beam was . Both ships had a designed draft of and a full load draft of . was at the waterline and long overall; with the clipper bow, her overall length was . Her beam was and a draft of standard and 7.2 m at full load. and were long overall, with beams of and drafts of standard and at full load.

Although nominally within the 10,000-ton limit, the ships of the class significantly exceeded the figure. and had a designed displacement of and a full load displacement of . s displacement increased slightly, to designed and full load. and grew heavier still, at designed and full load.

The ships' hulls were constructed from longitudinal steel frames. The hulls were divided into fourteen watertight compartments and a double bottom that extended for 72 percent of the length of the keel. The vessels had a flush deck and a fairly substantial superstructure that included a large, armored conning tower forward, a tower foremast. Amidships, the cruisers had a hangar and catapult for their Arado Ar 196 reconnaissance floatplanes. Further aft, the ships had a pole mainmast and smaller, secondary conning tower. The regarded the ships as good sea boats, with gentle motion. At low speed, however, they were affected unpredictably by wind and currents. The ships heeled up to fourteen degrees and lost up to 50% speed with the rudder hard over at high speed. The ships had a standard complement of 42 officers and 1,340 enlisted men. Wartime modifications increased the crew to 51 officers and 1,548 sailors. The ships carried several smaller vessels, including two picket boats, two barges, one launch, one pinnace, and two dinghies.

Machinery

The -class ships were powered by three sets of geared steam turbines. s and s engines were built by Blohm & Voss, while s turbines were built by Germaniawerft. The turbines installed on s and s engines were manufactured by Deschimag. Steam was provided in the first three ships by twelve ultra-high-pressure boilers. and were equipped with nine double-ended high-pressure boilers. s and s boilers were manufactured by Wagner, while the boilers for the other three ships were built by La Mont. On all ships, the boilers were vented through a single large funnel located amidships.

Each turbine drove a three-bladed screw that was in diameter. The ships' engines were rated at for a top speed of . They carried of fuel oil as designed, though the ships could carry up to . At a cruising speed of , the ships had a maximum range of .

Steering was controlled by a single rudder. and were equipped with three electricity plants with four diesel generators and six turbo-generators each; the diesel generators supplied 150 kW apiece, four of the six turbo-generators provided 460 kW, and the final pair provided 230 kW. Total electrical output was 2900 kW. , , and were equipped with three 150 kW diesel generators, four 460 kW turbo-generators, one 230 kW turbo-generator, and one 150 kW AC generator, for a total of 2870 kW. All five ships' electrical plants operated at 220 volts.

Armament

The three completed ships were armed with eight 20.3 cm SK C/34 guns in four twin turrets. The ships were supplied with between 960 and 1,280 rounds of ammunition, or 120 to 160 rounds per gun. The guns were mounted in Drh LC/34 turrets, which enabled depression to −10° and elevation to 37°. At maximum elevation, the gun could reach out to . It fired a projectile at a muzzle velocity of . The projectiles included armor-piercing shells, base-fuzed and nose-fuzed high-explosive (HE) warheads. Each ship was also supplied with 40 illumination rounds that weighed and had a muzzle velocity of . The four gun turrets built for were emplaced as coastal artillery pieces in the Atlantic Wall. Only the two forward turrets had been installed on when she was delivered to the Soviet Union.

The ships' heavy anti-aircraft battery consisted of twelve SK C/33 guns in twin mountings. These guns were supplied with a total of 4,800 rounds of ammunition. The mounts were the Dopp LC/31 type, originally designed for earlier SK C/31 guns. The LC/31 mounting was triaxially stabilized and capable of elevating to 80°. This enabled the guns to engage targets up to a ceiling of . Against surface targets, the guns had a maximum range of . The guns fired fixed ammunition weighing ; the guns could fire HE and HE incendiary rounds, as well as illumination shells. All three ships had four stabilized anti-aircraft director posts for directing the fire of the heavy anti-aircraft battery. and were equipped with the SL-6 model, whilst had the more modern SL-8.

Close-range anti-aircraft weaponry initially consisted of twelve SK C/30 guns and eight Flak 38 guns. The 3.7 cm gun was a single-shot gun, with a rate of fire of around 30 rounds per minute. At its maximum elevation of 85°, the gun had a ceiling of . The 2 cm gun was a magazine-fed automatic weapon, firing at up to 500 rounds per minute. Twenty and forty-round magazines were supplied for the guns; The guns were supplied with 16,000 rounds of ammunition. Later in the war, the light anti-aircraft batteries for and were modified. Four 3.7 cm guns were removed and the number of 2 cm guns had increased to twenty-eight. In 1944, s 3.7 cm guns were replaced by fifteen Flak 28 guns. By 1945, the ship's light anti-aircraft battery comprised twenty 4 cm guns and eighteen 2 cm guns; mounted sixteen 4 cm guns and fourteen 2 cm guns.

The ships' armament was rounded out by twelve torpedo tubes; they were mounted in four triple launchers on the ships' main deck. The ships carried twenty-four G7a torpedoes, twelve loaded in the tubes and one reload for each. The G7a torpedo carried a warhead. It had three-speed settings; in 1939, it could reach at , at , and at , its maximum speed setting. The radial engine was improved during the war, which improved performance. The ranges increased to , , and , respectively.

For minelaying purposes the ships could be equipped with maximum of rails on which different type of mines could be loaded, transported and thrown over the stern. The maximum load of mines was 140 tons. When carrying a full load of mines, counterweights had to be added in the double bottom of the hull. The standard mine was the EMC mine which was a contact mine and had a 300 kg explosive charge.

Armor

The five -class ships were protected by Krupp steel armor, of both and types. The ships had two armored decks to protect the ship from vertical attacks. The upper deck was thick amidships to protect the ships' vitals. At either end, the deck was reduced to thickness. The bow and stern was not protected by deck armor. The main armored deck was thick. Both decks were steel. The main armored belt was thick amidships and reduced to thick aft. An interior 20 mm thick torpedo bulkhead protected the ships' vitals from underwater attack.

The ships' main battery turrets were protected with thick faces and 70 mm thick sides. Their roofs were also 70 mm thick. The 10.5 cm guns were equipped with thick gun shields. The forward conning tower had thick sides and a thick roof. The rear conning tower was significantly less well armored, with only splinter protection. Their sides were 30 mm thick with a 20 mm thick roof. The anti-aircraft fire directors were also given splinter protection, with thick shields.

Construction