On 5 July, Hopton's army had driven Waller from his position at the indecisive Battle of Lansdowne. In doing so the Royalists suffered many casualties and desertions. Sir Bevil Grenville, the popular commander of Hopton's Cornish troops, was killed in the battle. Hopton himself was temporarily blinded the next day by an exploding ammunition cart. The explosion also left the Royalist army very short of gunpowder forcing them to withdraw towards Oxford, the Royalist capital, in order to get reinforcements and new supplies. Although Waller's army had been forced to withdraw, it remained intact, and Waller quickly obtained reinforcements from the Parliamentarian garrison of Bristol. He followed Hopton's army closely and on the night of 8 July he occupied Roundway Down, the high ground north of Devizes, to barr a further retreat by the Royalists. The Royalists fell back into the town and their commanders held a hasty council of war. It was agreed that Prince Maurice would break out and make for Oxford with the 300 cavalry remaining with the Royalist army. While Hopton's Cornish infantry defended Devizes, Maurice was to collect a relieving force from Oxford. Maurice and his 300 horse escaped just before Waller surrounded Devizes. Unaware of Maurice's escape to Oxford, Waller set up his guns and began a siege of the vulnerable unfortified town the next day. On 12 July he captured a convoy bringing ammunition to Hopton and demanded a surrender. The surrender was refused and the next morning the Royalist relief force appeared on Roundway Down. Maurice had reached Oxford late on 10 July. Lord Wilmot, Lieutenant General of Horse for King Charles set out almost at once for Devizes with 1,500 cavalry and two light "galloper guns", an early form of horse artillery, collecting Maurice's 300 horse on the way.
Battle
Early on the morning of 13 July, Wilmot's relieving force reached Roughridge Hill, north east of Devizes and fired two rounds from their guns as a signal to the besieged. They were organised as two strong brigades under Wilmot himself and Sir John Byron and a weaker brigade under Lord Crawford. Waller had been informed of their arrival, and he abandoned the siege and marched to Roundway Down, hoping to defeat Wilmot before Hopton could sally from Devizes against his rear. He deployed his infantry and artillery in the centre of his line, with cavalry on each flank. Recent findings of cannonballs and musket and pistol shot have suggested that the site of the battle was not on the highest point of the down, but close to Oliver's castle, the site of an Iron AgeHillfort in front of what is today the Roundway Covert. Although Waller held the higher ground, the Royalists attacked first. Wilmot's brigade attacked the Parliamentarian left. The leading troops of this Parliamentarian wing were a fully armoured regiment of cuirassiers, the London lobsters under Sir Arthur Haselrig. They appeared to have met Wilmot's charge at the halt, and were thrown into confusion and driven back into their second line. After a brief contest, they retreated in disorder. Byron attacked the Parliamentarian right, commanded by Waller, under fire from the guns and musketeers of their centre. Once again, the Parliamentarians halted to receive the charge, and were shaken by the clash. They too gave way and fled, pursued by Byron. Some of the fleeing Parliamentarians died when they were forced to gallop over "Oliver's Castle" and over an unseen precipice near Roundway village, now called locally "the Bloody Ditch". Wilmot's and Byron's troopers rallied and turned on the Parliamentarian centre. They captured at least four of the Parliamentarians' cannons and turned them on the infantry. The 2,000 Roundhead foot held out for a while, until Hopton's infantry, who had marched up from Devizes Castle, deployed to attack. The Roundheads then tried to retreat northwards, but failed and the survivors threw down their arms. About 600 Parliamentarian troops were killed and some 1,000 were captured.
Aftermath
Roundway Down was the greatest cavalry victory of the English Civil War. The Royalists christened the battle "Runaway Down". The defeat of an army arrayed in proper battle order on high ground by a column of cavalry that had just ridden down from Oxford was regarded as remarkable. Waller had previously been favoured to replace the Earl of Essex as lord general of the Parliamentarian armies. His defeat at Roundway Down made this impossible. Waller and his supporters criticised Essex for his perceived inactivity, which had allowed the royalists to detach Wilmot's cavalry from Oxford. The Parliamentarian field army in south-west England was destroyed, allowing the Royalists to capture the port and major city of Bristol a few weeks later; this period of Royalist successes was referred to as the "Royalist summer". The "village" of Roundway is today a small hamlet north of central Devizes, with a population of around 25 residents. There is a discussion of possible burial sites for the battle on the Devizes heritage website with an outline of the research evidence.
