Deal and the adjacent castles of Walmer and Sandown were constructed to protect the Downs in east Kent, an important anchorage formed by the Goodwin Sands which gave access to Deal Beach, on which enemy soldiers could easily be landed and an area the King knew well.[10] The stone castles were supported by a line of four earthwork forts, known as the Great Turf, the Little Turf Bulwark, the Great White Bulwark of Clay and the Walmer Bulwark, and a 2.5-mile-long (4.0 km) defensive ditch and bank.[11] Collectively the castles became known as the "castles of the Downes".[12][lower-alpha 1]