The fortified bridges of Charles the bald

Abstract

It is widely believed that Charles the bald built a network of fortified bridges in the Seine basin in the 860s to defend the West frankish kingdom against Viking invasion. However, a careful study of the primary sources reveals that only one bridge in the Seine valley was fortified, at Pont-de-l'Arche. Others were rebuilt in times of crisis in order to increased troop mobility, and in at least one instance to create a temporary barrier across the river. The latter tactic was also employed at Pont-de-l'Arche on one occasion, but such barriers would not have been permitted to remain in place once the immediate danger had passed, since the importance of the rivers as commercial arteries was such that they could not be allowed to remain closed for longer than was absolutely necessary. This helps to explain why Viking fleets were able to bypass the bridge at Pont-de-l'Arche even after fortification work had begun there in 862.There is in addition strong circumstantial evidence that the King also fortified a b...