In 1653, after the forcible dissolution of the Rump Parliament, the Army Council adopted the Instrument of Government which made Oliver Cromwell Lord Protector of a united "Commonwealth of England, Scotland and Ireland", inaugurating the period now usually known as the Protectorate. After Cromwell's death, and following a brief period of rule under his son, Richard Cromwell, the Protectorate Parliament was dissolved in 1659 and the Rump Parliament recalled, the start of a process that led to the restoration of the monarchy in 1660. The term Commonwealth is sometimes used for the whole of 1649 to 1660 – a period referred to by monarchists as the Interregnum – although for other historians, the use of the term is limited to the years prior to Cromwell’s formal assumption of power in 1653.
The Rump was created by Pride's Purge of those members of the Long Parliament who did not support the political position of the Grandees in the New Model Army. Just before and after the execution of King Charles I on 30 January 1649, the Rump passed a number of acts of Parliament creating the legal basis for the republic. With the abolition of the monarchy, Privy Council and the House of Lords, it had unchecked executive and legislative power. The English Council of State, which replaced the Privy Council, took over many of the executive functions of the monarchy. It was selected by the Rump, and most of its members were MPs. However, the Rump depended on the support of the Army with which it had a very uneasy relationship. After the execution of Charles I, the House of Commons abolished the monarchy and the House of Lords. It declared the people of England "and of all the Dominions and Territories thereunto belonging" to be henceforth under the governance of a "Commonwealth", effectively a republic.
In Pride's Purge, all members of parliament (including most of the political Presbyterians) who would not accept the need to bring the King to trial had been removed. Thus the Rump never had more than two hundred members (less than half the number of the Commons in the original Long Parliament). They included: supporters of religious independents who did not want an established church and some of whom had sympathies with the Levellers; Presbyterians who were willing to countenance the trial and execution of the King; and later admissions, such as formerly excluded MPs who were prepared to denounce the Newport Treaty negotiations with the King.
Most Rumpers were gentry, though there was a higher proportion of lesser gentry and lawyers than in previous parliaments. Less than one-quarter of them were regicides. This left the Rump as basically a conservative body whose vested interests in the existing land ownership and legal systems made it unlikely to want to reform them.
There were many disagreements amongst factions of the Rump. Some wanted a republic, but others favoured retaining some type of monarchical government. Most of England's traditional ruling classes regarded the Rump as an illegal government made up of regicides and upstarts. However, they were also aware that the Rump might be all that stood in the way of an outright military dictatorship. High taxes, mainly to pay the Army, were resented by the gentry. Limited reforms were enough to antagonise the ruling class but not enough to satisfy the radicals.
Despite its unpopularity, the Rump was a link with the old constitution, and helped to settle England down and make it secure after the biggest upheaval in its history. By 1653, France and Spain had recognised England's new government.