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
There was, further, the remnant of the old liberal minority
in the senate, which in former times had laboured to effect
a compromise with the reform party and the Italians, and was now
in a similar spirit inclined to modify the rigidly oligarchic
constitution of Sulla by concessions to the Populares.
There were, moreover, the Populares strictly so called,
the honestly credulous narrow-minded radicals, who staked property
and life for the current watchwords of the party-programme,
only to discover with painful surprise after the victory
that they had been fighting not for a reality, but for a phrase.
Their special aim was to re-establish the tribunician power, which Sulla
had not abolished but had divested of its most essential prerogatives,
and which exercised over the multitude a charm all the more mysterious,
because the institution had no obvious practical use and was
in fact an empty phantom--the mere name of tribune of the people,
more than a thousand years later, revolutionized Rome.