Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
On receiving these accounts, which appear to have first
opened the eyes of the Romans to the course and the object of
Hannibal, the consul had temporarily given up his expedition to Spain,
and had resolved in connection with the Celtic tribes of that region,
who were under the influence of the Massiliots and thereby under that
of Rome, to receive the Phoenicians on the Rhone, and to obstruct
their passage of the river and their march into Italy.
Fortunately
for Hannibal, opposite to the point at which he meant to cross, there
lay at the moment only the general levy of the Celts, while the consul
himself with his army of 22,000 infantry and 2000 horse was still in
Massilia, four days' march farther down the stream. The messengers of
the Gallic levy hastened to inform him. It was the object of Hannibal
to convey his army with its numerous cavalry and elephants across the
rapid stream under the eyes of the enemy, and before the arrival of
Scipio; and he possessed not a single boat.