Both ships served during World War I. "Moltke" participated in several major battles with the rest of the High Seas Fleet, including the battles of Dogger Bank and Jutland in the North Sea, and the Battle of the Gulf of Riga and Operation Albion in the Baltic Sea. At the end of the war, "Moltke" was interned with the majority of the High Seas Fleet at Scapa Flow while the ships' fate was being discussed during peace treaty negotiations. The ships were scuttled on 21 June 1919 to prevent their seizure by the Allies.