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

47. Whilst these things were going on at Veii, in the mean while the citadel and Capitol of Rome were in great danger. [2] For the Gauls either having perceived the track of a human foot where the messenger from Veii had passed, or having of themselves remarked the easy ascent by the rock at the temple of Carmentis, on a moonlight night, after they had at first sent forward an unarmed person, to make trial of the way, delivering their arms, whenever any difficulty occurred, alternately supported and supporting each other, and drawing each other up, according as the ground required, they reached the summit in such silence, that they [3??] not only escaped the notice of the sentinels, but of the dogs also, an animal extremely wakeful with respect to noises by night. The notice of the geese they did not escape, which, as being sacred to Juno, were spared though they were in the greatest scarcity of food. [4] Which circumstance was the cause of their preservation. For Marcus Manlius, who three years before had been consul, a man distinguished in war, being aroused from sleep by their cackling and the clapping of their wings, snatched up his arms, and at the same time calling the others to do the same, proceeds to the spot; and whilst the others are thrown into confusion, he struck with the boss of his shield and tumbles down a Gaul, who had already got footing on the summit; [5] and when the fall of this man as he tumbled threw down those who were next him, he slew others, who in their consternation had thrown away their arms, and caught hold of the rocks to which they clung. And now the others also having assembled beat down the enemy by javelins and stones, and the entire band, having lost their footing, were hurled down the precipice in promiscuous ruin. [6] The alarm then subsiding, the remainder of the night was given up to repose, (as far as could be done considering the disturbed state of their minds,) when the danger, even though past, still kept them in a state of anxiety. [7] Day having appeared, the soldiers were summoned by sound of trumpet to attend the tribunes in assembly, when recompence was to be made both to merit and to demerit; [8] Manlius was first of all commended for his bravery and presented with [p. 381]gifts, not only by the military tribunes, but with the consent of the soldiers, for they all carried to his house, which was in the citadel, a contribution of half a pound of corn an half a pint of wine: a matter trifling in the relation, but the [prevailing] scarcity had rendered it a strong proof of esteem, when each man, depriving himself of his own food, contributed in honour of one man a portion subtracted from his body and from his necessary requirements. [9] Then the guards of that place where the enemy had climbed up unobserved, we e summoned; [10] and when Quintus Sulpicius declared openly that he would punish all according to the usage of military discipline, being deterred by the consentient shout of the soldiers who threw the blame on one sentinel, he spared the rest. The man, who was manifestly guilty of the crime, he threw down from the rock, with the approbation of all. [11] From this time forth the guards on both sides became more vigilant on the part of the Gauls, because a rumour spread that messengers passed between Veii and Rome, and on that of the Romans, from the recollection of the danger which occurred during the night.