During the Hundred Years' War a French attack (1340) burned a manor house and took some prisoners, but failed to get into the town. In 1403 the town was burned by Breton raiders. In the late fifteenth century a 'castle quadrate' was constructed close to the area now known as The Barbican; it included four round towers, one at each corner, as featured on the city coat of arms. The castle served to protect Sutton Pool, which is where the fleet was based in Plymouth prior to the establishment of Plymouth Dockyard. In 1512 an Act of Parliament was passed for further fortifying Plymouth, and a series of fortifications were then built, including defensive walls at the entrance to Sutton Pool (across which a chain would be extended in time of danger). Defences on St Nicholas Island also date from this time, and a string of six artillery blockhouses were built, including one on Fishers Nose at the south-eastern corner of the Hoe. This location was further strengthened by the building of a fort (later known as Drake's Fort) in 1596, which itself went on to provide the site for the Citadel, established in the 1660s (see below).