Quickly informed of this march, Vercingetorix, at the prayer of the Arverni, who implored his succour, abandoned the country of the Bituriges. Cæsar had foreseen this; so he only remains two days amongst the Arverni, and, quitting them under the pretext of increasing his forces, he leaves the command to young Brutus, whom he enjoins to throw out his reconnoitring parties to as great a distance as possible, and promises to return at the end of three days. Having by this diversion drawn Vercingetorix southward, he proceeds in great haste to Vienne, arrives there unexpectedly, takes the newly-raised cavalry which he had sent thither, marches night and day, crosses the country of the Ædui, and directs his march towards the Lingones, where two legions were in winter quarters. By this extreme rapidity he seeks to prevent any evil design on the part of the Ædui. Scarcely has he arrived amongst the Lingones, when he sends orders to the other legions, two of which were on the frontiers of the Treviri, and the six others in the country of the Senones, to concentrate the whole army at Agedincum (_Sens_) before his march is known to the Arverni. As soon as Vercingetorix was informed of this movement, he returned with his army to the country of the Bituriges, and thence started to lay siege to Gorgobina (_Saint-Parize-le-Châtel_), an _oppidum_ of the Boii, who had settled, after the defeat of the Helvetii, near the confluence of the Allier and the Loire.[465] [Sidenote: Taking of Vellaunodunum, Genabum, and Noviodunum.]