 SMS Preussen was an armored frigate of the German Kaiserliche Marine . The ship was built by the AG Vulcan shipyard in Stettin in 1871 – 1876 ; she was commissioned into the fleet in July 1876 . She was the first large warship of the German navy built by a private shipyard ; all previous vessels had been ordered abroad or built by Royal or Imperial dockyards . Her main battery of four 26 cm ( 10 in ) guns was mounted in a pair of twin gun turrets amidships . 
