The Grand Duchy of Posen (German: Großherzogtum Posen; Polish: Wielkie Księstwo Poznańskie) was part of the Kingdom of Prussia, created from territories annexed by Prussia after the Partitions of Poland, and formally established following the Napoleonic Wars in 1815. Per agreements derived at the Congress of Vienna it was to have some autonomy. However, in reality it was subordinated to Prussia and the proclaimed rights for Polish subjects were not fully implemented. The name was unofficially used afterward for denoting the territory, especially by Poles, and today is used by modern historians to refer to different political entities until 1918. Its capital was Posen (Polish: Poznań).