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
The Samnites found new allies in the Umbrians of northern, and in the Marsi and Paeligni of central, Italy, and numerous volunteers even from the Hernici joined their ranks; but movements which might have decidedly turned the scale against Rome, had the Etruscans still remained under arms, now simply augmented the results of the Roman victory without seriously adding to its difficulties. The Umbrians, who gave signs of marching on Rome, were intercepted by Rullianus with the army of Samnium on the upper Tiber--a step which the enfeebled Samnites were unable to prevent; and this sufficed to disperse the Umbrian levies.
The war once more returned to central Italy. The Paeligni were conquered, as were also the Marsi; and, though the other Sabellian tribes remained nominally foes of Rome, in this quarter Samnium gradually came to stand practically alone. But unexpected assistance came to them from the district of the Tiber. The confederacy of the Hernici, called by the Romans to account for their countrymen found among the Samnite captives, now declared war against Rome (in 448)--more doubtless from despair than from calculation. Some of the more considerable Hernican communities from the first kept aloof from hostilities; but Anagnia, by far the most eminent of the Hernican cities, carried out this declaration of war.
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Reference address : https://www.ellopos.net/elpenor/rome/2-06-italians-rome.asp?pg=24