In June 1644 the Cavaliers suffered an enormous defeat at the Battle of Marston Moor. In September 1644 the Roundheads suffered an equally horrible defeat at the Battle of Lostwithiel. After Lostwithiel, the Parliamentarians were afraid that the King would march on London. Parliament had three armies at their disposal. The three armies met at Basingstoke and made plans to stop the King. The three armies numbered 19,000 men. The King had no intention of attacking London. He was more concerned with rescuing Banbury, Basing House and Castle Donnington that were under siege by the Roundheads.
King Charles led an army of 10,000 and rescued Banbury and Castle Donnington. The Roundheads marched toward Castle Donnington and prepared to fight him near the town of Newbury. The King’s army were in a very strong position. They were protected by two rivers and Castle Donnington’s artillery. To the west of the battlefield the King’s nephew Prince Maurice had built earthworks near the town of Sleep, where he placed more cannons. To the north of the battlefield was Shaw House, filled with tough Royalist soldiers.
Although Parliament had twice as many men, they didn’t want to attack the Cavaliers straight on. They decided to split their army and attack the King from the east and west at the same time. In order to accomplish this, they secretly marched 12,000 men, under the command of Sir William Waller, around the battlefield at night-time. Sir Edward Montagu was in command of the soldiers left behind. Montagu was supposed to launch his main attack when he heard Waller’s signal.
The battle began early in the morning. Montagu launched an unsuccessful assault against Shaw House. The attack was a trick designed to take the Royalists attention away from Waller as his army snuck up on the Cavaliers. But Waller was late. He didn’t arrive until 2.00 in the afternoon. Waller attacked Speen. His infantry captured Prince Maurice’s guns. Waller sent in cavalry, commanded by William Balfour and Oliver Cromwell. Balfour was successful, to begin with. He nearly succeeded in surrounding and capturing the King. But the King’s bodyguard rescued him and pushed Balfour back. Cromwell’s charge was a disaster. His normally unbeatable horse were defeated. With Parliament’s cavalry in confusion, the King’s infantry drove back Waller’s foot soldiers. Montagu never heard Wallers signal and didn’t support him in time. Around 4.00pm Montagu attacked Shaw house for the second time. The sun set. It was too dark to carry on fighting.
The battle was a draw. The King’s army left the battlefield at night and travelled to Oxford. For their failure to defeat the King, Waller and Montagu would lose their jobs and Parliament would create the New Model Army.