Skenfrith Castle () is a ruined castle in the village of Skenfrith in Monmouthshire, Wales. The fortification was established by the Normans in the wake of the invasion of England in 1066, to protect the route from Wales to Hereford. Possibly commissioned by William fitz Osbern, the Earl of Hereford, the castle comprised earthworks with timber defences. In 1135, a major Welsh revolt took place and in response King Stephen brought together Skenfrith Castle and its sister fortifications of Grosmont and White Castle to form a lordship known as the "Three Castles", which continued to play a role in defending the region from Welsh attack for several centuries. At the end of the 12th century, Skenfrith was rebuilt in stone. In 1201, King John gave the castle to a powerful royal official, Hubert de Burgh. During the course of the next few decades, it passed back and forth between several owners, including Hubert, the rival de Braose family, and the Crown. Hubert levelled the old castle and built a new rectangular fortification with round towers and a circular keep. In 1267 it was granted to Edmund, the Earl of Lancaster, and remained in the hands of the earldom, and later duchy, of Lancaster until 1825. Edward I's conquest of Wales in 1282 removed much of Skenfrith Castle's military utility, and by the 16th century it had fallen into disuse and ruin. The castle was placed into the care of the state by the National Trust in 1936, and is now managed by the Cadw heritage agency. History 11th–12th centuries Skenfrith Castle was built in the wake of the Norman invasion of England in 1066. Shortly after the invasion, the Normans pushed up into the Welsh Marches, where William the Conqueror made William fitz Osbern the Earl of Hereford; Earl William added to his new lands by then capturing the towns of Monmouth and Chepstow. The Normans used castles extensively to militarily subdue the Welsh, establish new settlements and exert their claims of lordship over the territories. Skenfrith Castle was one of a triangle of fortifications built in the Monnow valley around this time, possibly by Earl William himself, to protect the route from Wales to Hereford. The first castle on the site was built from earth and timber. The earldom's landholdings in the region were slowly broken up after William's son, Roger de Breteuil, rebelled against the King in 1075.