 It was garrisoned by about 80 men with a peak armament of around 20 cannon of various calibres.Despite its strategic importance, the castle and the defences of the Thames and Medway were badly neglected during the 17th century.The Dutch Republic mounted an unexpected naval raid in June 1667, and the Dutch fleet was able to breach the defences, capturing two warships and burning others at anchor in the river at Chatham, in one of the worst defeats suffered by the Royal Navy.