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
The consequences of this one campaign were immense; they were felt
for many centuries after. The Rhine had become the boundary
of the Roman empire against the Germans. In Gaul, which was no longer
able to govern itself, the Romans had hitherto ruled on the south
coast, while lately the Germans had attempted to establish themselves
farther up. The recent events had decided that Gaul was to succumb
not merely in part but wholly to the Roman supremacy,
and that the natural boundary presented by the mighty river was also
to become the political boundary.
The senate in its better times
had not rested, till the dominion of Rome had reached the natural
bounds of Italy--the Alps and the Mediterranean--and its adjacent
islands. The enlarged empire also needed a similar military
rounding off; but the present government left the matter
to accident, and sought at most to see, not that the frontiers
were capable of defence, but that they should not need to be defended
directly by itself. People felt that now another spirit
and another arm began to guide the destinies of Rome.