"Roundhead" was the name given to the supporters of the Parliament during the English Civil War. Also known as Parliamentarians, they fought against King Charles I and his supporters, the Cavaliers (Royalists), who claimed absolute power and the divine right of kings. The goal of the Roundhead party was to give the Parliament supreme control over executive administration.
Most Roundheads appear to have sought a constitutional monarchy, in place of the absolutist monarchy sought by Charles I. However, at the end of the Civil War in 1649, public antipathy towards the king was high enough to allow republican Roundhead leaders such as Oliver Cromwell to abolish the monarchy completely and establish the republican Commonwealth. The Roundhead commander-in-chief of the first Civil War, Lord Fairfax, remained a supporter of constitutional monarchy, as did many other Roundhead leaders such as Edward Montagu and the Earl of Essex, however this party was outmaneuvered by the more politically adept Cromwell and his radicals, who had the backing of the New Model Army and took advantage of Charles' perceived betrayal of England by allying with the Scots against Parliament.
England's many Puritans and Presbyterians were almost invariably Roundhead supporters, as were many smaller religious groups such as the Independents. However many Roundheads were Church of England, as were many Cavaliers.
Origins and background 
Some of the Puritans, but by no means all, wore their hair closely cropped round the head, or flat, and there was thus an obvious contrast between them and the men of courtly fashion with their long ringlets.
During the war and for a time afterwards Roundhead was a term of derision—in the New Model Army it was a punishable offence to call a fellow soldier a Roundhead. This contrasted with the term Cavalier to describe supporters of the Royalist cause. Cavalier also started out as a pejorative term—the first proponents used it to compare members of the Royalist party with Spanish Caballeros who had abused Dutch Protestants during the reign of Elizabeth I—but unlike Roundhead, Cavalier was embraced by those who were the target of the epithet and used by them to describe themselves.
Roundheads appears to have been first used as a term of derision toward the end of 1641, when the debates in Parliament in the Bishops Exclusion Bill were causing riots at Westminster. One authority said of the crowd which gathered there, "They had the hair of their heads very few of them longer than their ears, whereupon it came to pass that those who usually with their cries attended at Westminster were by a nickname called Roundheads". The demonstrators included London apprentices and Roundhead was a term of derision for them because the regulations to which they had agreed included a provision for closely cropped hair.
According to John Rushworth the word was first used on 27 December 1641 by a disbanded officer named David Hide, who during a riot is reported to have drawn his sword and said he would "cut the throat of those round-headed dogs that bawled against bishops".
However, Richard Baxter ascribes the origin of the term to a remark made by Queen Henrietta Maria at the trial of the Earl of Strafford earlier that year; referring to John Pym, she asked who the Roundheaded man was.
The principal advisor to Charles II, the Earl of Clarendon remarked on the matter, "and from those contestations the two terms of Roundhead and Cavalier grew to be received in discourse, ... they who were looked upon as servants to the king being then called Cavaliers, and the other of the rabble contemned and despised under the name of Roundheads."
Ironically, after Anglican Archbishop Laud made a statute in 1636 instructing all clergy to wear short hair, many Puritans rebelled to show their contempt for his authority and began to grow their hair even longer (as can be seen on their portraits) though they continued to be known as Roundheads. The longer hair was more common among the "Independent" and "high ranking" Puritans (which included Cromwell), especially toward the end of the Protectorate, while the "Presbyterian" (i.e. non-Independent) faction, and the military rank-and-file, continued to abhor long hair. By the end of this period some Independent Puritans were again derisively using the term Roundhead to refer to the Presbyterian Puritans.
Roundhead remained in use to describe those with republican tendencies up until the Exclusion Bill crisis of 1678–1681; the term was then superseded by Whig, initially another term with pejorative connotations. Likewise during Exclusion Bill crisis, the term Cavalier was replaced with Tory, a term introduced by the opponents of the Tories, and also initially a pejorative term.
- Roberts 2006,[page needed]
- Macaulay 1856, p. 105.
- Anonymous 1911.
- Worden 2009, p. 2.
- Anonymous 1911 cites Rushworth Historical Collections
- Anonymous 1911 cites Clarendon History of the Rebellion, volume IV. page 121.
- Hunt 2010, p. 5[verification needed]
- Hanbury 1844, pp. 118, 635.
- Worden 2009, p. 4.
- Macaulay, Thomas Babington (1856). The History of England from the Accession of James II 1. New York: Harper & Brothers. p. 105. ISBN 0-543-93129-3.
- Hanbury, Benjamin (1844). Historical Memorials Relating to the Independents Or Congregationalists: From Their Rise to the Restoration of the Monarchy 3. pp. 118, 635.
- Hunt, John (2010) . Religious Thought in England, from the Reformation to the End of Last Century; A Contribution to the History of Theology 2. General Books LLC. p. 5. ISBN 1-150-98096-6.
- Roberts, Chris (2006). Heavy Words Lightly Thrown: The Reason Behind Rhyme. Thorndike Press. ISBN 0-7862-8517-6.
- Worden, Blair (2009). The English Civil Wars 1640–1660. London: Penguin Books. ISBN 0-14-100694-3.