their return to the Continent. The fleet, under the command of Prince Charles, attempted to landed a fresh force in August, but despite three attempts the operation failed and suffered heavy losses. Deal surrendered on 25 August, followed by Sandown on 5 September. Interregnum and the Restoration Unlike many castles, the Device Forts avoided being slighted – deliberately damaged or destroyed – by Parliament during the years of the Interregnum. Many of the forts remained garrisoned with substantial numbers of men due to fears of a Royalist invasion, overseen by newly appointed governors; Netley was brought back into service due to the threat. Many were used to hold prisoners of war or political detainees, including Hull, Mersea, Portland, Southsea and West Cowes. During the First Anglo-Dutch War between 1652 and 1654, castles such as Deal were reinforced with earthworks and soldiers. Portland saw action during a three-day long naval battle between English and Dutch forces in the Portland Roads. Some sites fell out of use: Little Dennis Blockhouse – part of the complex of defences at Pendennis – and Mersea were decommissioned between 1654 and 1655, and Brownsea Castle was sold off into private hands. Charles II was restored to the throne in 1660 and reduced both the size and the wages of the garrisons across the kingdom. The Device Forts initially remained at the heart of the defences along the south coast, but their design was by now badly antiquated. Deal continued to play an important role in defending the Downs during the Second and Third Dutch Wars, supported by local trained bands, and castles such as Hurst, Portland and Sandgate remained garrisoned. Others, however, were decommissioned with Sandsfoot closing in 1665 following a dispute over the control of the defences, and Netley being abandoned to fall into ruin. Concerns about the Dutch threat were intensified after an unexpected naval raid along the Thames in 1667, during which Gravesend and Tilbury prevented the attack reaching the capital itself. In response, Charles made extensive improvements to his coastal defences. As part of this investments were made to Pendennis, Southsea and Yarmouth, while Tilbury was hugely expanded with an updated system of ramparts, bastions and moats at considerable cost. In the final phases of Charles's work, the castle and southern blockhouse at Hull were incorporated into a massive new fortification called the Citadel during the 1680s. Some of the Device Forts