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
After Hannibal had thus lost his most important acquisitions and
found himself hemmed in by degrees to the south-western point of the
peninsula, Marcus Marcellus, who had been chosen consul for the next
year (546), hoped that, in connection with his capable colleague
Titus Quintius Crispinus, he should be able to terminate the war by a
decisive attack. The old soldier was not disturbed by the burden of
his sixty years; sleeping and waking he was haunted by the one thought
of defeating Hannibal and of liberating Italy.
But fate reserved that
wreath of victory for a younger brow. While engaged in an unimportant
reconnaissance in the district of Venusia, both consuls were suddenly
attacked by a division of African cavalry. Marcellus maintained the
unequal struggle--as he had fought forty years before against Hamilcar
and fourteen years before at Clastidium--till he sank dying from
his horse; Crispinus escaped, but died of his wounds received
in the conflict (546).