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
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
When in the course of time a large portion of the landed property in Rome had passed into the hands of non-burgesses and thus the rights and duties of burgesses were no longer bound up with freehold property, the reformed constitution obviated this incongruous state of things, and the perils which it threatened, not merely temporarily but permanently, by treating the members of the community without reference to their political position once for all according to their freeholding, and imposing the common burden of war-service on the freeholders--a step which in the natural course of things could not but be followed by the concession of public rights.
The whole policy of Roman war and conquest rested, like the constitution itself, on the basis of the freehold system; as the freeholder alone was of value in the state, the aim of war was to increase the number of its freehold members. The vanquished community was either compelled to merge entirely into the yeomanry of Rome, or, if not reduced to this extremity, it was required, not to pay a war-contribution or a fixed tribute, but to cede a portion, usually a third part, of its domain, which was thereupon regularly occupied by Roman farms. Many nations have gained victories and made conquests as the Romans did; but none has equalled the Roman in thus making the ground he had won his own by the sweat of his brow, and in securing by the ploughshare what had been gained by the lance.
That which is gained by war may be wrested from the grasp by war again, but it is not so with the conquests made by the plough; while the Romans lost many battles, they scarcely ever on making peace ceded Roman soil, and for this result they were indebted to the tenacity with which the farmers clung to their fields and homesteads. The strength of man and of the state lies in their dominion over the soil; the greatness of Rome was built on the most extensive and immediate mastery of her citizens over her soil, and on the compact unity of the body which thus acquired so firm a hold.
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Reference address : https://www.ellopos.net/elpenor/rome/1-13-agriculture-trade-commerce.asp?pg=2