The second class of German dreadnoughts are, more or less, improved and enlarged versions of the preceding Nassau class. Armour protection and internal subdivision were enhanced, the main artillery calibre was upgraded from 28cm to the new 30,5cm standard, but otherwise nothing much changed. Originally, the four ships were supposed to be fitted with turbine engines, but since the respective engines were not ready in time, they were built with conventional triple expansion engines instead. These engines were more powerful than those on the Nassau class, so the top speed could be raised to 21 knots. The four new dreadnoughts, all named after German regions or states, entered fleet service in 1911 and 1912.