At length the revolt of the Fidenates, who expelled the Roman garrison, murdered the Roman envoys, and submitted to Lars Tolumnius, king of the Veientes, gave rise to a more considerable war, which ended favourably for the Romans; the king Tolumnius fell in combat by the hand of the Roman consul Aulus Cornelius Cossus (326 ?), Fidenae was taken, and a new armistice for 200 months was concluded in 329.

During this truce the troubles of Etruria became more and more aggravated, and the Celtic arms were already approaching the settlements that hitherto had been spared on the right bank of the Po.

When the armistice expired in the end of 346, the Romans on their part resolved to undertake a war of conquest against Etruria; and on this occasion the war was carried on not merely to vanquish Veii, but to crush it.
Conquest of Veii The history of the war against the Veientes, Capenates, and Falisci, and of the siege of Veii, which is said, like that of Troy, to have lasted ten years, rests on evidence far from trustworthy.

Legend and poetry have taken possession of these events as their own, and with reason; for the struggle in this case was waged, with unprecedented exertions, for an unprecedented prize.

It was the first occasion on which a Roman army remained in the field summer and winter, year after year, till its object was attained.