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
We plainly perceive that it was the especial aim of the Romans and Latins to separate the Aequi from the Volsci, and to become masters of the communications between them; in the region between the southern slope of the Alban range, the Volscian mountains and the Pomptine marshes, moreover, the Latins and the Volscians appear to have come first into contact and to have even had their settlements intermingled.(11)
11. To all appearance Velitrae, although situated in the plain, was originally Volscian, and so a Latin colony; Cora, on the other hand, on the Volscian mountains, was originally Latin.
In this region the Latins took the first steps beyond the bounds of their own land, and federal fortresses on foreign soil--Latin colonies, as they were called--were first established, namely: in the plain Velitrae (as is alleged, about 260) beneath the Alban range itself, and Suessa in the Pomptine low lands, in the mountains Norba (as is alleged, in 262) and Signia (alleged to have been strengthened in 259), both of which lie at the points of connection between the Aequian and Volscian territories.
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Reference address : https://www.ellopos.net/elpenor/rome/2-05-subjugation-latins-campanians.asp?pg=10