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
In the same manner Tuder in Umbria was stormed
by Marcus Crassus. A longer resistance was offered in Etruria
by Populonium and above all by the impregnable Volaterrae, which
gathered out of the remains of the beaten party an army of four
legions, and stood a two years' siege conducted first by Sulla
in person and then by the former praetor Gaius Carbo, the brother
of the democratic consul, till at length in the third year after
the battle at the Colline gate (675) the garrison capitulated on
condition of free departure.
But in this terrible time neither
military law nor military discipline was regarded; the soldiers
raised a cry of treason and stoned their too compliant general; a
troop of horse sent by the Roman government cut down the garrison
as it withdrew in terms of the capitulation. The victorious army
was distributed throughout Italy, and all the insecure townships
were furnished with strong garrisons: under the iron hand of the
Sullan officers the last palpitations of the revolutionary and
national opposition slowly died away.