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
Courageously it made its dispositions for the double conflict, the Transalpine Gauls and Insubres against the troops of Papus, the Alpine Taurisci and the Boii against the Sardinian infantry; the cavalry combat pursued its course apart on the flank. The forces were in numbers not unequally matched, and the desperate position of the Gauls impelled them to the most obstinate resistance.
But the Transalpine Gauls, accustomed only to close fighting, gave way before the missiles of the Roman skirmishers; in the hand-to-hand combat the better temper of the Roman weapons placed the Gauls at a disadvantage; and at last an attack in flank by the victorious Roman cavalry decided the day.
The Celtic horsemen made their escape; the infantry, wedged in between the sea and the three Roman armies, had no means of flight. 10,000 Celts, with their king Concolitanus, were taken prisoners; 40,000 others lay dead on the field of battle; Aneroestus and his attendants had, after the Celtic fashion, put themselves to death.
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Reference address : https://www.ellopos.net/elpenor/rome/3-03-extension-italy.asp?pg=35