The Battle of Roundway Down was fought on 13 July 1643 near Devizes, in Wiltshire during the First English Civil War. Despite being outnumbered and exhausted after riding overnight from Oxford, a Royalist cavalry force under Lord Wilmot won a crushing victory over the Parliamentarian Army of the West under Sir William Waller. Viewed as their most decisive victory of the war, the Royalists secured control of South West England which they held until late 1645. Two weeks later they captured the port of Bristol, allowing them to establish links with supporters in Ireland.