Most of the changes in the political structure of Europe between 1688 and 1721 arose in connection with five great wars: the Nine Years War, the War of the Spanish Succession, the Turkish wars of 1683–99 and 1714–18, and the Great Northern War. That these wars never merged into one European conflict suggests a tripartite division of Europe into west, north and south-east. Of course there were no hard and fast partitions between these regions. A number of States belonged to two or more: for example, Hanover and Brandenburg to both west and north, the Habsburg monarchy and Venice to west and south-east, Russia and Poland to the north and south-east. Nor was it uncommon for countries of one region to get involved in the affairs of another—almost always to redress the balance of forces in it or prevent innovations deemed harmful: as examples we can cite William III's rôle in the Altona settlement of 1689, Charles XII's in the Empire in 1706–7, the Habsburg intervention in the Turco-Venetian war in 1716. Yet attempts to call in the forces of another region in order positively to upset the existing order elsewhere, or to break a military deadlock nearer home, usually miscarried. The decline of French influence in Sweden and Brandenburg, Poland and Turkey, amounting to a breakdown of the classical ‘eastern barrier’ in the 1680s, indeed tended to sharpen the tripartite division of Europe. In the Nine Years War Louis XIV was no longer able to summon his northern allies to fight on his side, while William III was not strong enough to secure more than a few auxiliary troops from them.