and later ten L/30 quick-firing guns, a pair of machine guns, and five torpedo tubes, all submerged in the ship's hull. Preussens armor was made of wrought iron and backed with teak. The armored belt was arrayed in two strakes. The upper strake was thick; the lower strake ranged in thickness from . Both were backed with of teak. The gun turrets were protected by armor on the sides, backed by 260 mm of teak. Service history Construction – 1878 Preussen was ordered by the Imperial Navy from the AG Vulcan shipyard in Stettin; work on the ship was delayed by the start of the Franco-Prussian War. Her keel was laid down in 1871 under construction number 66, after the war ended in a Prussian victory and German unification. This was the first time a private German shipbuilder was given a contract to build a large warship for the navy. The ship was launched on 22 November 1873, and during the ceremony she was christened by Crown Princess Victoria. After completing fitting-out work, apart from her armament, she was towed to Swinemünde on 23 November 1875. The ship was commissioned into the German fleet on 4 July 1876 and then moved to Kiel, where her guns were installed at the (Imperial Shipyard). Although she was the third and final ship in her class to be laid down, she was the first to be launched and commissioned. This was because her two sisters, and , were built by newly established Imperial dockyards, while Preussen was built by an experienced commercial ship builder. After work on the ship was completed in late 1876, the ship began sea trials on 16 November. These were interrupted by the need to use the vessel's strengthened hull to break ice in the Baltic Sea for merchant vessels. This activity ended on 2 March 1877, allowing Preussen to resume trials, which concluded on 5 May. Two days later, she was assigned to the Ironclad Squadron to replace the ironclad , which was in need of an overhaul. The ironclad squadron, led by the flagship , departed for the Mediterranean Sea on 30 May in response to unrest in the Ottoman Empire related to the Russo-Turkish War; the violence threatened German citizens living there. The squadron, which also included the ironclad , the armored frigate , and the aviso , was commanded by (KAdm—Rear Admiral) Carl Ferdinand Batsch.