Coastal erosion
In 1883 architectural historian Hayter Lewis complained to the British Archaeological Association that more needed to be done to protect the ruins, contrasting their poor treatment with that of the other castles along the coast. Despite this, concerns continued to be raised about the safety of the ruins facing along the sea, and in 1894 the Royal Engineers blew up the bastions and the keep on the seaward side using guncotton. The town of Deal then bought the remains from the government for £35 for use as part of their local sea defences. Coastal erosion continued and between 1988 and 1989 the remains were encased in concrete to form a sea wall, although they remain vulnerable to further coastal erosion. The remains of the castle are protected under UK law as a scheduled monument.