King Charles I was executed on 30 January 1649, and on 17 March the Rump Parliament took the still more revolutionary step of abolishing the office of kingship, arguing that ‘for the most part, use hath been made of the regal power to oppress and impoverish and enslave the subject’. Two days later, by a further Act of Parliament, the House of Lords was declared ‘useless and dangerous’ and was likewise ‘wholly abolished’. After pausing anxiously for two months, Parliament went on to draw the obvious inference and duly proclaimed that ‘the people of England, and of all the dominions and territories thereunto belonging’ now constituted ‘a Commonwealth and Free State’ governed solely by the people's elected representatives. With this sequence of decisions, a republic was founded for the first and (so far) the only time in British history.

These unprecedented events stood in urgent need of legitimation, and several different strands of political thinking were immediately pressed into service. Some defenders of the commonwealth, including the Rump itself, sought to occupy the highest possible constitutional ground. They argued that Charles I had broken his contract with his people, and that the people's representatives had simply removed a tyrant and reestablished lawful authority under their own command. Others argued, more concessively, that all governments are manifestations of the will of God, and thus that the new regime, no less than its predecessor, ought to be regarded as providentially ordained.