Wigmore Castle was founded soon after the Norman Conquest to secure a strategically important part of the Welsh Marches. William fitzOsbern established an early earth-and-timber stronghold, and the Mortimer family gained the lordship before the end of the eleventh century. A motte, baileys, gates, walls, halls, and service buildings grew across the ridge. From this commanding position, the Mortimers controlled estates, roads, courts, and military obligations on a frontier where English and Welsh power overlapped.

The Mortimers repeatedly rebuilt Wigmore in stone as their wealth and ambitions expanded. Marcher privileges allowed them unusual authority to wage war, build castles, administer law, and acquire territory with limited royal supervision. The castle served a large household of relatives, knights, clerks, servants, craftspeople, and retainers. Chapels and comfortable chambers stood beside defensive works, while the nearby abbey provided a religious foundation and dynastic burial place. Wigmore was thus the administrative heart of a regional lordship, not merely a refuge during raids.

In the thirteenth and fourteenth centuries, Mortimer involvement in Welsh conquest and English politics brought both advancement and disaster. Roger Mortimer, first earl of March, escaped imprisonment, joined Queen Isabella against Edward II, and dominated government after the king's deposition. Edward III arrested and executed him in 1330, but the family later recovered its honors. Mortimer marriages eventually connected the earls of March to the royal succession, helping create the claim inherited by the House of York.

When Edward IV became king in 1461, Wigmore entered the Crown estate through his Mortimer ancestry. Royal ownership reduced the need for a resident magnate household, and maintenance declined. Later tenants occupied or reused parts of the complex, but roofs and ranges disappeared. During the English Civil War, the remaining defenses were reportedly rendered unusable to prevent a Royalist garrison. Abandonment, stone removal, vegetation, and erosion gradually produced the extensive wooded ruin visible today.

Modern conservation has treated Wigmore as an archaeological landscape rather than reconstructing it into an imagined complete castle. English Heritage stabilized vulnerable masonry while retaining vegetation that contributes to the ruin's character, and earthworks reveal baileys and approaches beyond the standing gatehouse and walls. Wigmore's national importance comes from the Mortimers' ascent from frontier lords to ancestors of kings. Its fragmentary condition also shows how quickly a political center could decline once inheritance transferred its estates and authority to the Crown, leaving local communities to reuse the surrounding agricultural land nearby.