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 Romans Opposed to the Etruscans in Veii
This rapid collapse of the Etruscan maritime power would be inexplicable but for the circumstance that, at the very time when the Sicilian Greeks were attacking them by sea, the Etruscans found themselves assailed with the severest blows oil every side by land. About the time of the battles of Salamis, Himera, and Cumae a furious war raged for many years, according to the accounts of the Roman annals, between Rome and Veii (271-280).
The Romans suffered in its course severe defeats. Tradition especially preserved the memory of the catastrophe of the Fabii (277), who had in consequence of internal commotions voluntarily banished themselves from the capital(5) and had undertaken the defence of the frontier against Etruria, and who were slain to the last man capable of bearing arms at the brook Cremera.
5. Cf. II. II. Coriolanus
But the armistice for 400 months, which in room of a peace terminated the war, was so far favourable to the Romans that it at least restored the -status quo- of the regal period; the Etruscans gave up Fidenae and the district won by them on the right bank of the Tiber.
We cannot ascertain how far this Romano-Etruscan war was connected directly with the war between the Greeks and the Persians, and with that between the Sicilians and Carthaginians; but whether the Romans were or were not allies of the victors of Salamis and of Himera, there was at any rate a coincidence of interests as well as of results.
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Reference address : https://www.ellopos.net/elpenor/rome/2-04-fall-etruscan-celts.asp?pg=8