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 army set out thither and reached the
town; but the siege was unsuccessful and without prospect of result,
and, when the king who had remained for a time with his troops in
front of the town went into the desert, the Roman general preferred
to pursue him.
This was precisely what Jugurtha intended in a
nocturnal assault, which was favoured by the difficulties of the
ground and the secret understanding which Jugurtha had with some in
the Roman army, the Numidians captured the Roman camp, and drove
the Romans, many of whom were unarmed, before them in the most
complete and disgraceful rout.
The consequence was a capitulation,
the terms of which--the marching off of the Roman army under the yoke,
the immediate evacuation of the whole Numidian territory, and the
renewal of the treaty cancelled by the senate--were dictated by
Jugurtha and accepted by the Romans (in the beginning of 645).