Titus Livius (Livy), The History of Rome, Book 5
D. Spillan, A.M., M.D., Ed.

37. Though danger of such magnitude was impending (so completely does Fortune blind the minds of men when she wishes not her threatening stroke to be foiled) a state, which against the Fidenatian and Veientian enemies, and other neighbouring states, had recourse to aid even from the most extreme quarters, and had appointed a dictator on [2??] many trying occasions, that same state now, when an enemy, never before seen or heard of, from the ocean and remotest regions [p. 369]of the earth, was advancing in arms against them, looked not for any extraordinary command or aid. [3] Tribunes, by whose temerity the war had been brought on them, were appointed to the chief direction of affairs, and even making less of the war than fame had represented it, held the levy with no greater diligence than used to be exercised for ordinary wars. [4] In the mean while the Gauls, on hearing that honour was even conferred on the violators of human law, and that their embassy was slighted, inflamed with resentment, over which that nation has no control, immediately snatched up their standards, and enter on their march with the utmost expedition. [5] When the cities, alarmed at the tumult occasioned by them as they passed precipitately along, began to run to arms, and the peasants took to flight, they indicated by a load shout that they were proceeding to Rome, taking up an immense space of ground, wherever they passed, with their horses and men, their troops spreading widely in every direction. [6] But fame and the messengers of the Clusians, and then of the other states one after another, preceding them, the rapid advance of the enemy brought the greatest consternation to Rome; [7] for, with their tumultuary troops hastily led on, they met them within the distance of the eleventh mile-stone, where the river Allia, descending from the Crustuminian mountains in a very deep channel, joins the river Tiber not far below the road. [8] Already all places in front and on each side were crowded with the enemy, and this nation, which has a natural turn for causeless confusion, by their harsh music and discordant clamours, filled all places with a horrible din.