Dunster Castle motte, or Upper Ward, and an area below shaped to form the bailey, or Lower Ward. Somerset became more stable in the aftermath of the post-invasion period and the unsuccessful 1068 rebellion against Norman rule. It was common in the period for the Normans to build religious houses to accompany major castles, and accordingly William de Mohun endowed a Benedictine priory at Dunster in 1090, along with its parent abbey at Bath. The River Avill was important for trade; the region around Dunster was rich with fisheries and vineyards, and Dunster Castle prospered. Stone fortifications were built on the site
Dunster Castle and Colonel Robert Blake led a Parliamentary force against Dunster in October. In November Blake began his siege of the castle, setting up his artillery in Dunster village and starting to dig tunnels to plant mines beneath the walls. The castle was briefly relieved by reinforcements in February 1646, but the siege was resumed and by April the Royalists situation was untenable – an honourable surrender was negotiated and a Parliamentary garrison installed. After the end of the Second English Civil War in 1649, however, Parliament decided to deliberately destroy, or slight, the defences of castles in key Royalist areas,