 Military unions of "European powers" in the medieval and early modern period were directed against the threat of Islamic expansion.Thus, in the wake of the Fall of Constantinople to the Turks in 1453, George of Podebrady, a Hussite king of Bohemia, proposed in 1464 a union of European, Christian nations against the Turks.In 1693, William Penn looked at the devastation of war in Europe and wrote of a "European dyet, or parliament", to prevent further war, without further defining how such an institution would fit into the political reality of Europe at the time.