Brummer-class cruiser

The Brummer class consisted of two light mine-laying cruisers built for the Imperial German Navy in World War I: SMS Brummer and SMS Bremse. When the war broke out, the Germans had only two older mine-laying cruisers. Although most German cruisers were fitted for mine-laying, a need for fast specialized ships existed. The Imperial Russian Navy had ordered a set of steam turbines for the Navarin from the AG Vulcan shipyard in Stettin. This machinery was confiscated on the outbreak of war and used for these ships. Both vessels were built by AG Vulcan.

The two ships laid a series of minefields during their career, though their most significant success came in October 1917, when they attacked a British convoy to Norway. They sank two escorting destroyers and nine of the twelve merchant ships from the convoy. They escaped back to Germany without damage. The two ships were interned at Scapa Flow after the end of the war, and were subsequently scuttled by their crews on 21 June 1919. Brummer was sunk in deep water and was never raised, but Bremse was brought up in 1929 and broken up for scrap in 1932–1933.

Design and construction
In 1914, AG Vulcan in Stettin was building two sets of high-powered steam turbines for the Russian Navy for use in their new battlecruiser Navarin, then under construction in Russia. After the outbreak of World War I in August 1914, which saw Germany and Russia on opposing sides, the German government seized the turbines. At that time, the Kaiserliche Marine possessed only two cruisers equipped for mine-laying operations, the cruisers SMS Nautilus and SMS Albatross. The Kaiserliche Marine ordered AG Vulcan to split Navarin's propulsion system in half and to design a pair of cruiser hulls around the engines. The ships were to be fast mine-layers, capable of mining an area under cover of darkness and quickly returning to port before they could be intercepted. They were designed to resemble the British Arethusa class cruisers to aid in their ability to operate off the British coast.

Design work on the ships was completed quickly in 1914. Brummer was laid down at the AG Vulcan shipyard in Stettin in early 1915. Work proceeded quickly, and the ship was launched on 11 December 1915. After the completion of fitting-out work, the ship was commissioned into the High Seas Fleet on 2 April 1916. Bremse followed her sister the same year at AG Vulcan. She was launched on 11 March 1916 and completed in less than four months; the ship was commissioned into the fleet on 1 July 1916. During construction, the shape of their bow and its resemblance to British cruisers was covered by sheet metal.

General characteristics
Brummer and Bremse were 135 m long at the waterline and 140.4 m long overall. They had a beam of 13.2 m and a draft of 6 m forward and 5.88 m aft. The ships had a designed displacement of 4385 MT, and at full combat load, they displaced 5856 MT. Their hulls were built with longitudinal steel frames. The hulls were divided into twenty-one watertight compartments and incorporated a double bottom that extended for forty-four percent of the length of the keel. Brummer differed slightly, as she had a row of portholes amidships that her sister Bremse did not have.

Brummer and Bremse were fitted with masts similar to the British Arethusa class cruisers, and similarly to the British ships, the masts could be lowered and stored on the superstructure deck. Their bow was also modeled on the Arethusa class ships to further disguise the vessels. The ships had a complement of 16 officers and 293 enlisted men. They carried several smaller vessels, including one picket boat, one barge, and two dinghies. The German Navy regarded the ships as excellent sea boats, having gentle motion. The ships were highly maneuverable and had a tight turning radius, and only lost slight speed in a head sea. In hard turns, they lost up to sixty percent speed. They were very crank, however.

Machinery
The two ships' propulsion systems consisted of two turbines powered by two coal-fired Marine Doppelkessel double-ended boilers and four oil-fired Öl-Marine double-ended boilers. The turbines drove a pair of three-bladed screws, which were 3.2 m in diameter. The engines were rated at 33000 shp for a top speed of 28 kn. On trials, Brummer reached 42797 shp while Bremse made 47748 shp; they averaged a top speed of 30.2 kn with a light load. The ships were capable of speeds up to 34 kn, though only in short bursts.

Coal storage was 300 MT as designed, though up to 600 MT could be carried. Fuel oil was initially 500 MT, and could be similarly increased to 1000 MT. At a cruising speed of 12 kn, the ships could steam for 5800 nmi. At a higher speed of 25 kn, the range fell considerably, to 1200 nmi. Electrical power was provided by two turbo generators and one diesel generator. Steering was controlled by a single, large rudder.

Armament and armor
The ships were armed with four 15 cm SK L/45 guns in single pedestal mounts; all four were placed on the centerline so all four guns could fire on the broadside. One was placed forward on the forecastle, a second was located between the first and second funnel and two were arranged in a superfiring pair aft. These guns fired a 45.3 kg shell at a muzzle velocity of 840 m/s. The guns had a maximum elevation of 30 degrees, which allowed them to engage targets out to 17600 m. They were supplied with 600 rounds of ammunition, for 150 shells per gun. Brummer and Bremse also carried two 8.8 cm L/45 anti-aircraft guns mounted on the centerline astern of the funnels. These guns fired a 10 kg shells at a muzzle velocity of 750 to 770 m/s. The ships were also equipped with a pair of 50 cm torpedo tubes with four torpedoes in a swivel mount amidships. Designed as mine-layers, they carried up to 450 mines, depending on the type. Two rails ran down the main deck to the stern to allow the mines to be dropped behind the ship.

The Brummer-class cruisers' armor was fabricated from Krupp cemented steel. The ships were protected by a waterline armored belt that was 40 mm thick amidships; the bow and stern were not armored. The deck was covered with 15 mm thick armor plate. Gun shields 50 mm thick protected the 15 cm gun battery crews. The conning tower had 100 mm thick sides and a 20 mm thick roof. Atop the conning tower was the bridge, which included a splinter-proof chart house. All three funnels were equipped with a steel glacis for splinter protection.

Service
After their commissioning, Brummer and Bremse served with the High Seas Fleet, including on a sortie into the North Sea in October 1916. The ships laid a minefield off Norderney in January 1917 and guarded minesweepers between March and May that year. In October 1917, Admiral Reinhard Scheer sent the two ships to attack a British convoy to Norway to divert forces protecting convoys in the Atlantic. Scheer chose Brummer and Bremse because of their high speed and large radius of action. Shortly after dawn on 17 October, the two cruisers attacked the convoy, which consisted of twelve merchant ships, two destroyers, and two armed trawlers. The German ships quickly sank the escorting destroyers and nine of the twelve cargo vessels. The British Admiralty was not informed of the attack until Brummer and Bremse were safely steaming back to Germany.

Along with the most modern units of the High Seas Fleet, Brummer and Bremse were included in the ships specified for internment Scapa Flow by the victorious Allied powers. The ships steamed out of Germany on 21 November 1918 in single file, commanded by Rear Admiral Ludwig von Reuter. Reuter believed that the British intended to seize the German ships on 21 June 1919, and so he ordered the ships to be sunk at the next opportunity. On the morning of 21 June, the British fleet left Scapa Flow to conduct training maneuvers, and at 11:20 Reuter transmitted the order to scuttle his ships. Brummer sank at 13:05; she was never raised for scrapping and remains on the bottom of Scapa Flow. Bremse sank at 14:30 and was ultimately raised on 27 November 1929 and broken up for scrap in 1932–1933 in Lyness.