Boys commanded a division of the Earl Rivers's Royalist Regiment consisting of 200 foot, 25 horse, and 4 guns, which remained throughout the siege.
On 31 July 1644, Donnington Castle was attacked by a division of the New Model Army of 3000 horses and dragoons, under the command of Lieutenant-General John Middleton, but without any artillery support.
About a month later, on 29 September, Colonel Jeremy Horton began a 12-day blockade laying siege to Donnington, having raised a battery at the foot of the hill, near Newbury he was able to shatter the southern towers of the castles medieval defenses and reduce a part of the wall to rubble.
On 27 October, the second battle of Newbury was fought, and Colonel Sir John Boys secured the King's artillery under the walls of Donnington castle.
Some time after 14 November 1645, Oliver Cromwell himself turned his attention to the problem of the Royalist stronghold of Donnington castle, and in the following spring a furious bombardment with cannon and mortars was ordered.
During August 1648, he made a futile attempt to raise the Siege of Walmer Castle in Deal, one of the Cinque Ports, and customary home of the Lord Warden.
[1] A few years later, on 8 October 1664, Sir John Boys died at his house at Bonnington and was buried in the parish church of Goodnestone-next-Wingham (near Canterbury) in Kent.