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
Romanization of the Entire of Italy
The boundary of the Alps was reached, in so far as the whole flat country on the Po was either rendered subject to the Romans, or, like the territories of the Cenomani and Veneti, was occupied by dependent allies. It needed time, however, to reap the consequences of this victory and to Romanize the land. In this the Romans did not adopt a uniform mode of procedure.
In the mountainous northwest of Italy and in the more remote districts between the Alps and the Po they tolerated, on the whole, the former inhabitants; the numerous wars, as they are called, which were waged with the Ligurians in particular (first in 516) appear to have been slave-hunts rather than wars, and, often as the cantons and valleys submitted to the Romans, Roman sovereignty in that quarter was hardly more than a name.
The expedition to Istria also (533) appears not to have aimed at much more than the destruction of the last lurking-places of the Adriatic pirates, and the establishment of a communication by land along the coast between the Italian conquests of Rome and her acquisitions on the other shore. On the other hand the Celts in the districts south of the Po were doomed irretrievably to destruction; for, owing to the looseness of the ties connecting the Celtic nation, none of the northern Celtic cantons took part with their Italian kinsmen except for money, and the Romans looked on the latter not only as their national foes, but as the usurpers of their natural heritage.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/3-03-extension-italy.asp?pg=38