Castle, near Newbury), which had been isolated while he had been campaigning in the west. King Charles was joined briefly by Prince Rupert, who was ordered to march into Gloucestershire in an attempt to draw some of the Parliamentarian armies after him. The Parliamentarians, however, did not follow Rupert. As a result, the manoeuvre divided the Royalist forces, rather than those of Parliament. By the time that King Charles arrived in Berkshire with his army, the Earl of Essex had assembled three Parliamentarian armies and positioned them to block the Royalists from advancing on London. By 19 October Waller was at Basingstoke where he was joined by the Earl of Manchester with the Eastern Association army the next day. The Earl of Essex also arrived at Basingstoke on 20 October with an army composed largely of elements of the cavalry and infantry that had survived the battle at Lostwithiel. On 22 October, Charles relieved Donnington Castle. He knighted Lieutenant Colonel John Boys, the commander of its garrison, and promoted him to colonel. He hoped to relieve Basing House next, but the combined Parliamentarian armies were too strong for him to risk an advance. He therefore waited around Newbury for Rupert, and another detachment under the Earl of Northampton which had been sent to relieve Banbury, to rejoin him. Dispositions and plans Charles' army held three strong points: Donnington Castle north of Newbury, Shaw House northeast of the town and the village of Speen to the west. The River Kennet prevented the Parliamentarians making any outflanking move to the south, but the small River Lambourn divided the Royalists at Speen and Newbury from those at Shaw and Donnington Castle. Shaw House and its grounds including some Iron Age embankments incorporated into the defences, were defended by Lord Astley, with three "tertias" or brigades of infantry under his son, Sir Bernard Astley, Colonel Thomas Blagge and Colonel George Lisle. Speen was held by Rupert's brother Prince Maurice, with a mixed detachment from the Royalist forces from the west country. Charles's cavalry under George, Lord Goring were in reserve. They were divided into four brigades under Goring himself, Lord Wentworth, the Earl of Cleveland and Sir Humphrey Bennett. The Earl of Brentford was the Lord General, and Charles's deputy Lord Hopton commanded the artillery. Early on 26 October, the combined Parliamentarian armies advanced to Clay Hill, a few miles east of Newbury, where