The Congress Kingdom of Poland was created out of the Duchy of Warsaw, a French client state, at the Congress of Vienna in 1815 when the great powers reorganized Europe following the Napoleonic wars. The Kingdom was created on part of the Polish territory that had been partitioned between Russia, Austria and Prussia, and then transformed into the Duchy of Warsaw by Napoleon Bonaparte in 1807. After Napoleon's 1812 defeat, the fate of the Duchy of Warsaw was dependent on Russia. Prussia insisted on the Duchy being completely eliminated; after Russian troops reached Paris in 1812, Tsar Alexander I intended to annex the Duchy and parts of Lithuanian-Belarusian lands which were historically in the Polish–Lithuanian Commonwealth. However, both Austria and the United Kingdom strongly disapproved of the idea, Austria issuing a memorandum on returning to the 1795 resolutions with support from the United Kingdom under George IV, Prime Minister Robert Jenkinson and the British delegate to the Congress, Robert Stewart, Viscount Castlereagh.