Titus Livius (Livy), The History of Rome, Book 9
Benjamin Oliver Foster, Ph.D., Ed.

37. this expedition of the consul's, instead of putting an end to the war, only gave it a wider range. for the district lying about the base of Mount Ciminius had felt the devastation, and had aroused not only Etruria to resentment but the neighbouring parts of Umbria also. [2] so an army came to Sutrium that was larger than any they had raised before; and not only did they move forward their camp, out of the woods, but even, in their [p. 307]eagerness for combat, came down into the plain at¹ the earliest opportunity in battle formation. [3] at first, after forming up, they stood still in their positions, having left their enemies room to draw up opposite. then, finding the Romans in no haste to engage them, they advanced up to the rampart. [4] when they saw that even the outguards had retired within the works, they began shouting to their generals, to have their rations for the day sent out to them from the camp; they would wait under arms, they said, and either that night, or at daybreak at the latest, attack the enemy's stockade. The Roman army was every whit as restless, but was restrained by the general's authority. [5] it was about the tenth hour of the day² when the consul bade the soldiers sup, and commanded them to be armed and ready at whatever hour of the day or night he might give the signal. [6] in a brief address he magnified the Samnite wars and belittled the Etruscans: there was no comparison, he said, between the two enemies, or between their numbers; moreover, he had an additional weapon in concealment; they should know about it when the time came; until then it must remain a secret. [7] by these obscure hints he sought to engender a belief that the enemy were being betrayed, in order to revive the spirits of his men, which were damped by the numbers of their enemies; and the fact that the Etruscans had thrown up no breastworks where they lay lent colour to the insinuation.

refreshed with food, the soldiers gave themselves up to sleep, and at about the fourth watch were awakened without noise and put on their armour. [8] mattocks were issued to the soldiers' servants, that they might [p. 309]level the rampart and fill up the trenches. [9] The line³ was drawn up inside the fortifications, and selected cohorts were posted at the exits. then, on the signal being given a little before dawn, which on summer nights is the time of deepest sleep, the rampart was thrown down, and the Romans, rushing out in battle —formation, fell upon their enemies, who were lying all about the field. [10] some were slain without even stirring in their sleep, some were but half awake, the greatest number were reaching in terror for their weapons. only a few were given time to arm themselves; and even these, with no definite standard to follow and no leader, the Romans routed and chased from the field. some made for the camp and others for the mountains, as they fled this way and that. The forests afforded the surer refuge; for the camp, being situated in the plain, was captured the same day. [11] orders were issued that all gold and silver be brought to the consul; the rest of the booty went to the soldiers. on that day the enemy lost sixty thousand slain or captured.

some historians relate that this famous battle was fought on the other side of the Ciminian Forest, near Perusia, and that Rome was in a panic lest the army should be surrounded and cut off in that dangerous defile by the Tuscans and Umbrians rising up on every hand. [12] but, wherever it was fought, the Romans were the victors. and so from Perusia and Cortona and Arretium, which at that time might be the chief cities of the nations of Etruria, ambassadors came to Rome to sue for peace and an alliance. they obtained a truce for thirty years.