Résumé
The point of Hannibal's departure from New Carthage in Iberia, in 218 bc, and his subsequent march along the Mediterranean coast to the Pyrénées and on to the Rhône Basin, has been reconstructed by ancient historians with considerable accuracy. The latter 400-km phase through the Alps, however, has been the subject of some controversy as to whether the Punic Army followed a southern versus a northern invasion route, or some intermediate variant. What is certain from the ancient texts is that Hannibal was trapped by Gallic tribes in a large defile—a gorge large enough to hold the entire army—along the approach to the high col of passage on to the Po River Plains of northern Italia. The entrapment involved an enfilade attack planned by an unknown Gallic commander, a military operation that nearly decimated the Punic Army. Previous arguments as to the location of the defile have hinged on inconclusive topographic, geological and geomorphic assessments. New data from palaeobotanical reconstruction of the northern approach route show the Gorges de la Bourne and the Gorge du Bréda, astride the Isère River, to have been forest covered during the invasion, which would have made the Gallic assault impossible. The existing evidence argues for a southern route, the approach through the narrow defile of the Combe de Queyras, with passage over the Col de la Traversette, as argued by Sir Gavin de Beer nearly a half century ago. Narrowing the approach route focuses on sites worth geoarchaeological exploration.