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
Strange as it may seem, we can yet understand why the Romans now,
after king Bocchus had commenced the war, began to make most zealous
exertions to secure his friendship, which they had at first slighted
and thereafter had at least not specially sought; by doing so they
gained this advantage, that no formal declaration of war took place
on the part of Mauretania. King Bocchus was not unwilling to return
to his old ambiguous position: without dissolving his agreement with
Jugurtha or dismissing him, he entered into negotiations with the
Roman general respecting the terms of an alliance with Rome.
When
they were agreed or seemed to be so, the king requested that, for
the purpose of concluding the treaty and receiving the royal captive,
Marius would send to him Lucius Sulla, who was known and acceptable
to the king partly from his having formerly appeared as envoy of
the senate at the Mauretanian court, partly from the commendations of
the Mauretanian envoys destined for Rome to whom Sulla had rendered
services on their way. Marius was in an awkward position.