The Protectorate in the context of "English Separatist"

British republicans seek to replace the United Kingdom's monarchy with a republic led by an elected head of state. Monarchy has been the form of government used in the United Kingdom and its predecessor domains almost exclusively since the Middle Ages, except for a brief interruption from 1649–1660, during which a nominally republican government did exist under the leadership of Oliver Cromwell.

After Cromwell's Protectorate fell and the monarchy was restored, governing duties were increasingly handed to Parliament, especially as a result of the Glorious Revolution of 1688. The adoption of the constitutional monarchy system made the argument for full republicanism less urgent. It was once again a topic of discussion during the late 18th century with the American Revolution, and grew more important with the French Revolution, when the concern was how to deal with the French Republic on their doorstep. This led to a widespread anti-republican movement in Britain, and the issue was dormant for a time.

The Commonwealth of England, enlarged in 1653 as the Commonwealth of England, Scotland and Ireland, was the political structure during the period from 1649 to 1660 when the Kingdom of England was dissolved into a republic after the end of the Second English Civil War and the trial and execution of Charles I. The republic's existence was declared through "An Act declaring England to be a Commonwealth", adopted by the Rump Parliament on 19 May 1649. Power in the early Commonwealth was vested primarily in the Parliament and a Council of State. During the period, fighting continued, particularly in Ireland and Scotland, between the parliamentary forces and those opposed to them, in the Cromwellian conquest of Ireland and the Anglo-Scottish war of 1650–1652.

In 1653, after dissolution of the Rump Parliament, the Army Council adopted the Instrument of Government, by which Oliver Cromwell was made 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, starting 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 – called by some 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 Puritans were English Protestants in the 16th and 17th centuries who sought to rid the Church of England of what they considered to be Roman Catholic practices, maintaining that the Church of England had not been fully reformed and should become more Protestant. Puritanism played a significant role in English and early American history, especially in the Protectorate in Great Britain, and the earlier settlement of New England.

Puritans were dissatisfied with the limited extent of the English Reformation and with the Church of England's toleration of certain practices associated with the Catholic Church. They formed and identified with various religious groups advocating greater purity of worship and doctrine, as well as personal and corporate piety. Puritans adopted a covenant theology, and in that sense they were Calvinists (as were many of their earlier opponents). In church polity, Puritans were divided between supporters of episcopal, presbyterian, and congregational types. Some believed a uniform reform of the established church was called for to create a godly nation, while others advocated separation from, or the end of, any established state church entirely in favour of autonomous gathered churches, called-out from the world. These Separatist and Independents became more prominent in the 1640s, when the supporters of a presbyterian polity in the Westminster Assembly were unable to forge a new English national church.

English Dissenters or English Separatists were Protestants who separated from the Church of England between the 16th and 19th centuries. English Dissenters opposed state interference in religious matters and founded their own churches, educational institutions and communities. They tended to see the established church as too Catholic, but did not agree on what should be done about it.

Some Dissenters emigrated to the New World, especially to the Thirteen Colonies and Canada. Brownists founded the Plymouth Colony. The English Dissenters played a pivotal role in the religious development of the United States and greatly diversified the religious landscape. Some originally agitated for a wide-reaching Protestant Reformation of the established Church of England, and they flourished during the Protectorate under Oliver Cromwell.

In Welsh and English church history, Independents were a Puritan group who advocated local congregational control of religious and church matters, without any wider geographical hierarchy, either ecclesiastical or political. They were particularly prominent during the Wars of the Three Kingdoms as well under the Commonwealth and Protectorate. The New Model Army became the champion of Independent religious views and its members helped carry out Pride's Purge in December 1648.

Unlike their Presbyterian allies, Independents rejected any state role in religious practice, including the Church of England, and advocated freedom of religion for most non-Catholics. Their religious views led some to back radical political groups such as the Levellers, who supported concepts like Republicanism, universal suffrage and joint ownership of property.