 After the four s had been replaced by the four "Nassau"s, three of the "Siegfried"-class ships—, , —and the unique coastal defense ship "Oldenburg" were the next slated to be replaced.The "Helgoland"-class ships—SMS "Helgoland", SMS "Ostfriesland", SMS "Thüringen", and SMS "Oldenburg"—were ordered under the provisional names "Ersatz Siegfried, Ersatz Oldenburg, Ersatz Beowulf," and "Ersatz Frithjof", respectively.The "Helgoland"-class ships were longer than their predecessors, at overall.