The siege of Chester occurred over a 16-month period between September 1644 and February 1646 during the First English Civil War. In the engagement, Sir William Brereton and the Parliamentarians were ultimately successful in taking possession of the city and Royalist garrison commanded by Lord Byron.

Chester city walls consist of a defensive structure built to protect the city of Chester in Cheshire, England. Their construction was started by the Romans when they established the fortress of Deva Victrix between 70 and 80 [CE]. It originated with a rampart of earth and turf surmounted by a wooden palisade. From about 100 CE they were reconstructed using sandstone, but were not completed until over 100 years later. Following the Roman occupation nothing is known about the condition of the walls until Æthelflæd refounded Chester as a burgh in 907. The defences were improved, although the precise nature of the improvement is not known. After the Norman conquest, the walls were extended to the west and the south to form a complete circuit of the medieval city. The circuit was probably complete by the middle of the 12th century.