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 census lists of the Roman burgesses furnished the commentary on
these words. From the end of the Hannibalic war down to 595 the numbers
of the burgesses were steadily on the increase, the cause of which is
mainly to be sought in the continuous and considerable distributions
of domain-land:(22) after 595 again, when the census yielded 328,000
burgesses capable of bearing arms, there appears a regular falling-off,
for the list in 600 stood at 324,000, that in 607 at 322,000, that
in 623 at 319,000 burgesses fit for service--an alarming result for a
time of profound peace at home and abroad.
If matters were to go on
at this rate, the burgess-body would resolve itself into planters and
slaves; and the Roman state might at length, as was the case with the
Parthians, purchase its soldiers in the slave-market.
