Dunster Castle front and square towers, set within the older castle walls and overlooked by the keep above. The building was decorated in the latest styles, including ornamental plaster ceilings. The project ran almost three times over budget, costing Luttrell more than £1,200. In the 1640s the English Civil War broke out between the supporters of King Charles I and Parliament. Thomas Luttrell, George's eldest son, initially supported Parliament and after the outbreak of war William Russell, the Duke of Bedford and Parliamentary commander in Devon and Somerset, ordered him to increase the garrison at Dunster to resist a potential Royalist attack.
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,