The Welsh Marches, the borderlands between England and Wales, contain the highest concentration of motte-and-bailey castles in the region—unsurprising given its history of frequent conflict. Disputes over the borderlands date back to the Iron Age. The Romans later established forts at Chester, Gloucester, and Caerleon in an effort to control the rebellious Welsh. In the late 8th century, King Offa of Mercia built Offa's Dyke, the first significant border barrier, which still marks parts of the England-Wales boundary today.

The arrival of the Normans in 1066 transformed the Marches into a distinct political entity. The term "March" comes from the Anglo-Saxon mearc, meaning "boundary." While a few Norman castles, such as those at Ewyas Harold, Richard’s Castle, and Hereford, existed before the Norman Conquest, it was William the Conqueror who formalized efforts to subdue the borderlands. To secure the region, he appointed trusted allies Hugh d’Avranches, Roger de Montgomerie, and William FitzOsbern as the Earls of Chester, Shrewsbury, and Hereford, respectively. These Marcher lords governed independently of both the English monarchy and the Welsh princes. They could build castles, administer laws, wage wars, establish towns, and claim royal privileges, such as treasure troves and plunder.

Major centers of power emerged in Chester, Shrewsbury, and Hereford, alongside a network of strategic border castles, including Chepstow, Monmouth, Ludlow, Goodrich, and Montgomery.

The Domesday Book of 1086 first recorded the term "March of Wales." The Marcher lords actively encouraged immigration from across the Norman-Angevin realms, attracting Bretons, Flemings, Normans, and English settlers. They also promoted trade through ports such as Cardiff. New towns like Chepstow, Monmouth, Ludlow, and Newtown became thriving trade hubs, often focused on English settlement.

Despite these efforts, the Welsh frequently launched attacks into English territory and supported rebellions against Norman control, ensuring that the borderlands remained a contested and volatile region for centuries.

History of the Welsh Marches