Royalist cavalry and infantry decisively defeated Sir William Waller's Parliamentarian army near Devizes in Wiltshire on 13 July 1643. Many fleeing soldiers were killed or captured after being driven towards steep ground. The victory removed Parliament's principal field army in western England.

Royalist writers celebrated Roundway Down as a spectacular providential triumph. Parliamentarian accounts instead emphasised misfortune and the need for more disciplined forces, anticipating arguments for military reorganisation.