According to Tacitus (Histories 2.14), Fabius Valens, after hearing of the threat to Gallia Narbonensis, responded as follows: He despatched two cohorts of Tungrian infantry, four squadrons of horse, and all the cavalry of the Treviri under the command of Julius Classicus.
Part of these troops were retained for the defence of the colony of Forum Julii, for it was feared, that if the whole [Vitellianist] army were sent by the route through the interior, the [Othonian] fleet might make a rapid movement on the unprotected coast.
A rash attack on behalf of the Vitellian auxiliaries led to them being surrounded: The conflict commenced without delay, the enemy's line of battle being so arranged, that part of the levies from the fleet, who had a number of rustics among their ranks, were posted on the slope of the hills which border on the coast, the Prætorians fully occupying the level ground between the hills and the shore, while on the sea was the fleet, moored to the land and ready for action, drawn up in line so as to present a formidable front.
The squadrons of the Treveri charged the enemy incautiously, and found themselves encountered in front by the veteran troops, while on the flanks they were also annoyed by showers of stones from the rustic band, who were skilful throwers, and who, mixed up as they were among the regular soldiers, whether cowardly or brave, were all equally bold in the moment of victory.
The sentinels were cut down, the camp stormed, and the panic reached the ships, till, as the alarm gradually subsided, they again assumed the offensive under the protection of some neighbouring heights which they had occupied.