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
It seemed, however, not advisable to leave to this more remote community alien in race from the Roman such communal independence as was still retained by the subject communities of Latium; the Caerite community received the Roman franchise not merely without the privilege of electing or of being elected at Rome, but also subject to the withholding of self-administration, so that the place of magistrates of its own was as regards justice and the census taken by those of Rome, and a representative (-praefectus-) of the Roman praetor conducted the administration on the spot--a form of subjection, which in state-law first meets us here, whereby a state which had hitherto been independent became converted into a community continuing to subsist -de jure-, but deprived of all power of movement on its own part.
Not long afterwards (411) Falerii, which had preserved its original Latin nationality even under Tuscan rule, abandoned the Etruscan league and entered into perpetual alliance with Rome; and thereby the whole of southern Etruria became in one form or other subject to Roman supremacy. In the case of Tarquinii and perhaps of northern Etruria generally, the Romans were content with restraining them for a lengthened period by a treaty of peace for 400 months (403).
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Reference address : https://www.ellopos.net/elpenor/rome/2-04-fall-etruscan-celts.asp?pg=28