Goring the night before, refused to discuss this and asked them to return later in the day. A fresh assault began and the garrison surrendered without loss of life. The capture of the castle left Portsmouth's position untenable and the town surrendered. A significant Parliamentarian garrison was then installed in the castle to keep it from being retaken. The castle was primarily used as a prison during the interregnum and the early days of the Restoration. Concerns about a potential Dutch attack grew, however, and in 1665 King Charles II commissioned his Dutch-born master engineer, Sir Bernard de Gomme, to carry out a major scheme to improve the defences of Portsmouth, including Southsea Castle. Funding and poor organisation meant that the work did not begin until the 1680s. It included constructed an earthwork glacis around the castle; a new castle gate; four projecting turrets; and a redesign of the central keep. A large, stone plaque above the gatehouse entrance, bearing Charles' coat of arms, is dated 1683. When opposition grew in 1688 against the Catholic King James II, the military establishment around Portsmouth was controlled by the King's illegitimate son, James FitzJames, the Duke of Berwick. Revolution broke out and for a period Portsmouth and its defences were important to the King as a potential exit route for the Royal Family to France; by late December, however, this route was no longer needed. George Legge, the Baron Dartmouth, pressurised FitzJames to hand over control of Southsea Castle to the Protestant Captain Carter on 18 December and Portsmouth surrendered to the revolution two days later. The traveller Celia Fiennes, who visited the castle in 1690, observed that it was "very fine, but I think it is but of little strength and service." 18th – 19th centuries The east side of the castle was badly damaged in an explosion in August 1759, caused after cooking sparks fell onto gunpowder stored in the castle by the 72nd Regiment of Foot; 17 men, women and children were killed. Probably as a consequence of this event, a new powder store called the Firebarn was built outside the north side of the castle. By the second half of the century, the castle was in poor condition and, according to one contemporary account, only garrisoned by "an old sergeant and three or four men who sell cakes and ale". The Master–General of the Ordnance, Charles Lennox, the