 In the end, the raid marked the end of the castle's career as a fortress.New and more powerful forts were built farther down the Medway and on the Isle of Grain with the aim of preventing enemies reaching Chatham, thus making the castle redundant.It was converted into "a Place of Stores and Magazines" in 1668 with a new purpose of supplying munitions to naval warships anchored in the Medway or the Swale.