ABSTRACT
Charles the Bald ruled the West Franks from AD 843 to 877. During these years his kingdom took the brunt of the Danish Viking attacks, mainly concentrated on the Seine and Loire rivers, with Paris and Orleans as principal targets. The location of these works has been associated, with the 13th-century enceinte of Pont-de-l'Arche on the south bank of the Seine, together with its associated medieval bridging site, some 5 km from the modern commune of Pitres. Archaeomagnetic dating depends upon the fixing of the current direction of the geomagnetic field in materials containing iron compounds when they were heated or deposited. An intensive measurement programme and rapid sampling and processing methods have produced a usable reference curve for Great Britain, where archaeomagnetic dating is beginning to be used routinely. The material dated was clearly fired during an attack on the fort and the burning therefore post-dates construction.
