Historical clue formulations

• Ally of Britain during the Seven Years' War — 2020-11-21
• German kingdom of old — 2016-09-20
• Otto von Bismarck's realm — 2011-10-11
• Realm of Otto von Bismarck — 2008-03-02
• King Frederick I's realm — 2007-04-01
• Wilhelm I ruled it — 2007-03-25
• Where Wilhelm I ruled — 2002-11-24