1653 saw the initial union of Scotland with England. It was the first time that Scotland and England had been fully united as a single polity under a single constitution. The experiment lasted barely five years, for while the political union survived the remainder of the Protectorate, it effectively collapsed in 1659-60 and was reversed at the Restoration. The road to full political union had been opened by the Scots’ continuing support for the royalist cause after the execution of Charles I, causing the English republican regimes of the early 1650s to deploy England’s military might against them. The defeat of Scottish-royalist armies and the conquest and occupation of Scotland itself by English forces made possible a political and constitutional union which was assumed in the new written constitution of December 1653 – proclaimed to be a constitution for ‘the Commonwealth of England, Scotland and Ireland’ – but which was fleshed out and given substance by various measures issued by the Protector and his Council during 1654. In particular, several conciliar ordinances of spring and summer 1654 made clear the form and nature of the union, provided a statutory basis for the new secular and ecclesiastical administration of Scotland and began the process of remoulding Scotland to bring it closer to English ways and forms.