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
Another
remarkable instance of the Roman practice of turning to account for
their own interest the variances between the orders in the dependent
communities by favouring the aristocracy, is furnished by the
treatment which Volsinii met with in 489. There, just as in Rome,
the old and new burgesses must have stood opposed to one another,
and the latter must have attained by legal means equality of political
rights.
In consequence of this the old burgesses of Volsinii resorted
to the Roman senate with a request for the restoration of their old
constitution--a step which the ruling party in the city naturally
viewed as high treason, and inflicted legal punishment accordingly on
the petitioners. The Roman senate, however, took part with the old
burgesses, and, when the city showed no disposition to submit, not
only destroyed by military violence the communal constitution of
Volsinii which was In recognized operation, but also, by razing the
old capital of Etruria, exhibited to the Italians a fearfully palpable
proof of the mastery of Rome.