An example where the balance of power was forming was in England when they decided on a foreign policy that would preserve the balance between Spain and France, which later evolved into balance of power politics. There have been many attempts to falsify the balance of power theory and there have been some realists who have pointed out cases in international systems other than modern Europe where the balance has failed. The balance of power was first implemented internationally in Europe in the 17th century, in the aftermath of the Treaty of Westphalia of 1648. This peace formalized a system that had emerged among the great European powers during the early part of the century, including the recognition of state sovereignty in the international system. States, eager to find paths to secular peace after about a century of wars based on religious and ideological differences, gradually embraced the logic that underlies balance-of-power theory, and by the end of the 17th century, it was the approach of the European nation. States to international relations and foreign policy. During this period, Britain became familiar with using this system to its advantage, routinely playing the role of balancer to keep hegemonic aspirations in check and to become a central power in determining what the balance would be in the European system. This is a role that Britain would continue to play throughout the 17th and 18th centuries