If the low marshland through which the Yare and the Waveney now wind their way to the sea was at the time when the Romans established their system of fortifications, a wilderness of bog and fen, impassable either by ship or on foot, we can understand the importance of these spots on the river-sides where the enemy could get from their boats on to the highlands of Norfolk and Suffolk. The conflict of opinion among antiquarians as to the true site of the Roman Garianonum has made the conditions of the area immediately beneath Burgh Castle in the Roman period, a familiar subject of discussion. Whether Burgh Castle or Caister was the Roman Garianonum, the disputants took it for granted that it was some place near the entrance of the river from which it took its name; but they appear to have overlooked the point that if there were any river channel near either Burgh or Caister which could be attributed to the Yare, the estuarine condition of the interior must have already passed away. When this inland area was an arm of the sea, as it has been so often described, the rivers which meet at Yarmouth must have lost their channels and their names several miles further west. The Yare would have terminated at Norwich or Reedham, the Waveney at Beccles, and the Bure somewhere about Wroxham. The Yare could have had no claim to give its name to any place near the present coast, either Burgh or Caister. The Orwell is still an arm of the sea and it is not called after either the Gipping or the Stour. The Romans probably named their fortress at Burgh from the Yare, rather than the Waveney because the river Yare was the common waterway from the Roman camp at Caister on the Taes to the sea. The massive fortress of Burgh Castle could be safely held by a small force for a long time against any enemy who might succeed in effecting a landing on Lothingland itself, and if cavalry were kept there, as we are told they were, mounted messengers could be sent off as soon as a hostile fleet appeared, who would be able to carry the intelligence to head quarters at Caister, via Oulton and Beccles or Bungay, before the enemy could get very far up either river. The peculiar arrangement of the walls of Burgh Castle, which while they presented an impregnable defence on the North, East and South sides, left the west side with an easy slope down to the level of the river, unprotected, can only be explained by supposing with Camden and Spelman that the area between the river and the cliff, which is now marsh, was then an impassable morass, which offered an insuperable obstacle to the approach of a hostile force either by ship or on foot. {10}