The New Model Army or New Modelled Army was a standing army formed in 1645 by the Parliamentarians during the First English Civil War, then disbanded after the Stuart Restoration in 1660. It differed from other armies employed in the 1639 to 1653 Wars of the Three Kingdoms in that members were liable for service anywhere in the country, rather than being limited to a single area or garrison. To establish a professional officer corps, the army's leaders were prohibited from having seats in either the House of Lords or House of Commons. This was to encourage their separation from the political or religious factions among the Parliamentarians.

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.