After the Parliamentary victory at the Battle of Marston Moor, which was fought 2 July 1644, the north of England was largely under Parliamentary control apart from areas close to Royalist garrisons such as Lathom House.
The garrison did not capitulate quickly, but when it became clear that no relief could be expected, and supplies were running short, famine forced Colonel Rawstorne's hand and he surrendered at discretion to Colonel Egerton on 2 December 1645.