Titus Livius (Livy), The History of Rome, Book 7
Benjamin Oliver Foster, Ph.D., Ed.

11. And in fact the combat was of so great¹ consequence to the issue of the whole war, that the army of the Gauls withdrew in trepidation from their camp on the succeeding night and crossed over into the territory of Tibur. There they formed a military alliance with the Tiburtes, and having been liberally assisted by them with provisions, they soon departed and went into Campania. [2] This was the reason why in the following year the consul Gaius Poetelius Balbus, when his colleague Marcus Fabius Ambustus had been appointed to the campaign with the Hernici, was commanded by the people to march against the men of Tibur. [3] To aid their allies, the Gauls returned from Campania, and the cruel devastations which ensued in the districts of Labici, Tusculum, and Alba were clearly instigated and directed by the Tiburtes. [4] Against the Tiburtine foe the state was satisfied to be commanded by a consul; but the Gallic invasion required the appointment of a dictator. The choice fell on Quintus Servilius Ahala, who designated Titus Quinctius master of the horse, and, instructed by the senate, made a vow to celebrate the great games, in the event of a successful termination of the war. [5] Directing the consular army to remain where they were, in order to confine the Tiburtes to their own field of action, the dictator administered the oath to all the young men, none of whom endeavoured to avoid the service. [6] The battle was fought not far from the Colline [p. 391]Gate. The Romans put forth all their strength² in full sight of their parents and their wives and children. These are powerful incentives to courage even when unseen, but being then in full view, set the soldiers on fire with a sense of honour and compassion. [7] The slaughter was great on both sides, but at last the Gallic army was driven off. In their flight they turned towards Tibur, as though it had been the stronghold of the Gallic war; as they straggled on, they encountered the consul Poetelius, not far from the town, and when the Tiburtes came out to their assistance they were beaten back through the gates along with the Gauls. [8] The affair was admirably handled by the consul as well as by the dictator. And the other consul Fabius defeated the Hernici —at first in little skirmishes, but ultimately in one remarkable battle, in which the enemy attacked with all their forces. [9] The dictator, having handsomely lauded the consuls in the senate and before the people, even giving them the credit for his own achievements, resigned his office. Poetelius celebrated a double triumph over the Gauls and the Tiburtes: it was thought enough for Fabius that he should enter the City in an ovation.

The Tiburtes ridiculed the triumph of Poetelius. Where was it, they asked, that he had fought a battle with them? [10] A handful of people had gone outside the gates to look on at the flight and panic of the Gauls, and finding that they too were attacked and that all who came in the way of the Romans were cut down without discrimination, had retired within their walls; this was the great achievement that the Romans had deemed worthy of a triumph! [11] That they might not regard it as too wonderful and [p. 393]great a thing to cause a flurry at their enemy's³ gates, they should themselves behold a greater panic in front of their own walls.