Towards the end of the third century AD the ever increasing Saxon raids, necessitated the strengthening of the coastal defences. Around AD 270, Roman army units moved into Dover to construct a new “Fort of the Saxon Shore”. They ignored the old Classis Britannica Fort and built anew, although the corners of the two forts did overlap. The new fort enclosed a number of civilian buildings to the north of the earlier fort and the west wall went straight through the west end of the Painted House.Over 1000 feet of the south and west wall of the fort have been traced. The massive defensive wall was nearly 10 feet thick, reinforced at intervals along its length by great stone bastions and a ditch nearly 40 feet wide and 10 feet deep. Within the walls have been found the remains of at least 11 timber built structures, metalled roads and a postern gate with footbridge. It also appears that the military bath-house dating from about AD 140-160 was reused within the walls of the fort which now enclosed it.The fort seems to have been occupied at least until the first half of the 5th century and there is some evidence of occupation into the 6th century.A late 4th century document mentions nine forts under the command of the Count of the Saxon Shore: Branodunum (Brancaster, Norfolk), Gariannonum (Burgh Castle, Norfolk), Othona (Bradwell-on-Sea, Essex), Regulbium (Reculver, Kent), Rutupiae (Richborough, Kent), Dubris (Dover), Portus Lemanis (Lympne, Kent), Anderitum (Pevensey Castle, East Sussex), Portus Adurni (Portchester Castle, Hampshire). The coloured photo of Portchester Castle (bottom right) gives an idea of what the fort at Dover might have looked like.