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
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Massilia against Caesar
But at this point his opponents also had been active. Lucius Domitius, who was nominated by the senate in Caesar's stead as governor of Transalpine Gaul, had proceeded from Corfinium--as soon as Caesar had released him--along with his attendants and with Pompeius' confidant Lucius Vibullius Rufus to Massilia, and actually induced that city to declare for Pompeius and even to refuse a passage to Caesar's troops. Of the Spanish troops the two least trustworthy legions were left behind under the command of Varro in the Further province; while the five best, reinforced by 40,000 Spanish infantry-- partly Celtiberian infantry of the line, partly Lusitanian and other light troops--and by 5000 Spanish cavalry, under Afranius and Petreius, had, in accordance with the orders of Pompeius transmitted by Vibullius, set out to close the Pyrenees against the enemy.
Caesar Occupies the Pyrenees - Position at Ilerda
Meanwhile Caesar himself arrived in Gaul and, as the commencement of the siege of Massilia still detained him in person, he immediately despatched the greater part of his troops assembled on the Rhone--six legions and the cavalry--along the great road leading by way of Narbo (Narbonne) to Rhode (Rosas) with the view of anticipating the enemy at the Pyrenees. The movement was successful; when Afranius and Petreius arrived at the passes, they found them already occupied by the Caesarians and the line of the Pyrenees lost.
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Reference address : https://www.ellopos.net/elpenor/rome/5-10-brundisium-pharsalus-thapsus.asp?pg=36