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 Rome on the other hand no serious preparations had
been made. It was reported, indeed, that restless movements were
occurring in Italy, and that the communities of the allies maintained
a remarkable intercourse with each other; but instead of calling the
citizens in all haste to arms, the governing corporation contented
itself with exhorting the magistrates in the customary fashion to
watchfulness and with sending out spies to learn farther particulars.
The capital was so totally undefended, that a resolute Marsian officer
Quintus Pompaedius Silo, one of the most intimate friends of Drusus,
is said to have formed the design of stealing into the city at the
head of a band of trusty associates carrying swords under their
clothes, and of seizing it by a coup de main. Preparations were
accordingly made for a revolt; treaties were concluded, and arming
went on silently but actively, till at last, as usual, the insurrection
broke out through an accident somewhat earlier than the leading
men had intended.