which lasted until the Earl's death in 1651. When Derby besieged Manchester on 26 September, Birch was part of the garrison that held out until the Royalists retreated on 1 October, a victory that boosted Parliamentary morale in the area. In December, he was promoted major in a regiment commanded by Colonel Ralph Assheton, MP for Liverpool in the Long Parliament. He was present at the capture of Preston in February 1643, a significant victory that isolated Royalist forces in North-East Lancashire. One of his colleagues was George Booth, who later led Booth's Uprising in 1659. In 1643, Birch was appointed to the Lancashire Sequestration Committee, responsible for imposing fines on Royalists, and also colonel of a regiment of infantry in the Northern Association. He was made governor of Liverpool in June 1644, shortly before it was taken by Prince Rupert on his march north. Defeat at the Battle of Marston Moor in July cost the Royalists the North-West; Liverpool was retaken in November and Birch was given a garrison of 600 to hold the port. His regiment took part in the June 1646 siege of Goodrich Castle, one of the last actions of the First Civil War. Victory exacerbated divisions within Parliament; most of the leadership in Lancashire were moderate Presbyterians, among them Ralph Assheton, Alexander Rigby, Richard Standish and Sir Richard Hoghton. They were concerned by the radicalism of the religious Independents who dominated the New Model Army, such as Congregationalists like Oliver Cromwell and Thomas Birch. However, when the Second English Civil War began in 1648, the Lancashire leaders remained loyal to Parliament and fought at Preston in August. The Earl of Derby still held the Isle of Man for Charles I; Birch arrested his two daughters and held them in Liverpool Castle as a guarantee for his good behaviour. The breaking point for many moderates was the decision to put Charles I on trial for treason, followed by his execution on 30 January 1649. Along with his cousin John, Sir Richard Wynn, MP for Liverpool, was excluded by Pride's Purge in December 1648; Assheton, Rigby, Sir Richard Hoghton, and others were dismissed from the army following the 1650 Militia Act. Birch was one of the few who retained their positions, replacing Wynn as MP for Liverpool in October 1649, and being appointed colonel of the Lancashire militia; for the next few years, he was the senior