Among the mistakes in the new historical atlas (the subject of an earlier posting) is the identification of the river Sabis, where Caesar defeated the Nervians, with the modern Sambre. It is true that the words resemble each other, but that’s about all evidence there is for this identification.
A much more plausible place is the little river Selle, which empties itself into the Scheldt near modern Valenciennes. The obvious objection is that Selle does not look like Sabis at all, but looks can be deceptive. In 706, the river was called Save; in 964; we find a reference to the Seva; the change to Sevelle is a normal development in the twelfth and thirteenth century, and in 1476, presto, the little stream was known as Selle.
This identification also explains why the Nervians could surprise the Roman invaders. The Selle is crossed by a very ancient road, about which I’ve blogged before, which Caesar used: he writes that he left for the Nervians from the Ambiani, who lived near modern Amiens. The legions just took the main road, and were nearly defeated at a place that is now called Saulzoir, in northern France.
Pierre Turquin, ‘La Bataille de la Selle (du Sabis) en l’ An 57 avant J.-C.’ in Les Études Classiques 23/2 (1955), 113-156