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
A patrician matron, who was married to a leading plebeian that had
attained to the highest dignities of the state, was on account of this
misalliance expelled from the circle of noble dames and was refused
admission to the common festival of Chastity; and in consequence of
that exclusion separate patrician and plebeian goddesses of Chastity
were thenceforward worshipped in Rome.
Doubtless caprices of this
sort were of very little moment, and the better portion of the
clans kept themselves entirely aloof from this miserable policy of
peevishness; but it left behind on both sides a feeling of discontent,
and, while the struggle of the commons against the clans was in itself
a political and even moral necessity, these convulsive efforts to
prolong the strife--the aimless combats of the rear-guard after the
battle had been decided, as well as the empty squabbles as to rank
and standing--needlessly irritated and disturbed the public and
private life of the Roman community.