The mid 17th century was one of the most dramatic and turbulent times in British history. It was an age when Scotland shaped and changed the face of Britain. From 1637 to 1660 the two countries were extremely close and their relationship underwent profound changes. Scotland went from being the ally of the English parliament in the early 1640s, to becoming a conquered province of England in 1651. Although later admitting to a full parliamentary union with England, Scotland remained under military occupation until 1660. The conquest of Scotland by the English army was the culmination of a long period of hostility between the two countries whose roots lie entangled in the years of political and military alliance of the early 1640s. The road to open war was marked not only by a breakdown in Anglo-Scottish relations, but also by a radical realignment of political power within each country. When the final breach came, it was as much a product of domestic relations as it was of international relations.