The term "Cavalier" was first used by Roundheads as a term of abuse for the wealthier royalist supporters of King Charles I and his son Charles II of England during the English Civil War, the Interregnum, and the Restoration. It was later adopted by the Royalists themselves. Although it referred originally to political and social attitudes and behaviour, of which clothing was a very small part, it has subsequently become strongly identified with the fashionable clothing of the court at the time. Prince Rupert, commander of much of Charles I's cavalry, is often considered to be an archetypal Cavalier.
Prince Rupert of the Rhine, often considered to be an archetypal Cavalier
Lord John Stuart and his Brother, Lord Bernard Stuart, c. 1638, by Sir Anthony van Dyck. Both Lord John Stewart and Lord Bernard Stewart died in the English Civil War, fighting on the Royalist side.
Triple Unite gold coin of 1644: the Latin legend translates as "The religion of the Protestants, the laws of England and the liberty of Parliament. Let God arise and His enemies be scattered."
Charles I in Three Positions, the triple portrait of Charles I by Anthony van Dyck
Roundheads were the supporters of the Parliament of England during the English Civil War (1642–1651). Also known as Parliamentarians, they fought against King Charles I of England and his supporters, known as the Cavaliers or Royalists, who claimed rule by absolute monarchy and the principle of the divine right of kings. The goal of the Roundheads was to give to Parliament the supreme control over executive administration of the country/kingdom.
A Roundhead as portrayed by John Pettie (1839–1893)
A Roundhead inquisitor asks a son of a Cavalier, "And when did you last see your father?"—William Frederick Yeames (1878).