 It was rebuilt by 1669 to a design by Bernard de Gomme, who also designed Tilbury Fort further upriver.Two additional fortifications, the Half Moon Battery and Cavalier Battery, were subsequently added to further strengthen the defences.The Royal Commission recommended that de Gomme's red brick fortification and the two later batteries, which were incapable of withstanding modern guns, should be replaced by an armoured artillery fort on the same site.