The Battle of Selby, fought on 11 April 1644, was an important Parliamentary victory in the struggle for Yorkshire during the English Civil War. Selby stood beside the River Ouse, with roads and waterways connecting it to York and the surrounding countryside. A Royalist garrison under John Belasyse occupied the town. Its position offered a useful base, but the same rivers, flooded ground and restricted approaches that helped its defence could also obstruct an escape once attackers broke through the perimeter.

The Parliamentary army brought together forces associated with Lord Ferdinando Fairfax, his son Thomas Fairfax and Sir John Meldrum. Their attack formed part of a broader campaign in which the Royalists faced increasing pressure across northern England. Scottish intervention on Parliament's side had altered the balance of the war, while local commanders still depended upon supplies, garrisons and control of communications. Selby therefore mattered beyond its size: defeating its defenders could weaken the Royalists' ability to maintain an effective military network around York.

Parliamentary troops attacked the town's defended approaches and eventually forced their way inside. Thomas Fairfax played a prominent part in the fighting, and the Royalist position collapsed as attackers penetrated the streets. Belasyse was captured with a substantial portion of his force, together with military supplies. Accounts differ over precise numbers and particular movements, so the battle is better understood as a coordinated assault on a constrained urban position than as a sequence of securely identifiable individual encounters at modern street corners.

The defeat contributed to the Royalists' withdrawal towards York, where the Marquess of Newcastle's army became the focus of a major siege. Selby did not itself decide the northern campaign, but it helped create the circumstances that led to the confrontation at Marston Moor on 2 July 1644. That later battle involved much larger armies and had wider consequences. Keeping the two actions distinct shows how a successful attack on a garrison could influence a campaign before its best known decisive engagement.

Selby's battlefield is now largely an inhabited townscape rather than an open field preserved in its wartime condition. Changes to buildings, roads, drainage and the riverside complicate attempts to reconstruct the action. The surviving street pattern and the relationship between town and river nevertheless help explain the problems faced by attackers and defenders. Reading the landscape alongside contemporary accounts reveals a Civil War fought through working communities, where homes and routes of trade became military obstacles and the capture of a relatively small town carried consequences across Yorkshire.