Titus Livius (Livy), The History of Rome, Book 5
Benjamin Oliver Foster, Ph.D., Ed.

8. The ensuing year had for consular tribunes¹ Gaius Servilius Ahala (for the third time), Quintus Servilius, Lucius Verginius, Quintus Sulpicius, Aulus Manlius (for the second time), and Manius Sergius [p. 29](for the second time). In their term of office, while² everyone was intent on the war with Veii, the garrison at Anxur was neglected; [2] soldiers were given furlough, Volscian traders were admitted without discrimination, and, the sentinels at the gates being suddenly overpowered, the town was taken. [3] Not many soldiers perished, because they were all, except the sick, occupied, like sutlers, with trafficking in the country-side and the towns near by. [4] Nor were things any better at Veii, which was at that time the nation's chief concern; for the Roman commanders showed more jealousy of one another than spirit in dealing with the enemy, whose forces moreover were enlarged by the unexpected accession of the Capenates and the Faliscans. [5] These two Etruscan peoples, being nearest in situation, believed that if the Veientes were conquered it would be their turn next to face a Roman invasion. The Faliscans, besides, had incurred hostility on their own account, because they had been mixed up before in the war with Fidenae.³ [6] So they exchanged embassies, bound themselves by an oath, and their armies suddenly appeared before Veii. It happened that they attacked the camp at that point where the tribune Manius Sergius was in command, and great was the terror they inspired, since the Romans thought that all Etruria had risen and was come with a mighty array against them. [7] The same belief roused up the Veientes in the town. Thus a two-fold attack was directed against the camp. [8] The soldiers rallied into groups, facing now this way and now that, yet were unable either quite to confine the Veientes within the siege-lines, or to ward off the attack upon their own defences and protect [p. 31]themselves from the enemy outside. Their only⁴ hope was if help should come from the larger camp, so that the legions might face different ways, some of them confronting the Capenates and Faliscans, and others the sortie of the townsfolk. [9] But that camp was under the command of Verginius, who was privately hated by Sergius and returned his enmity. [10] This man, though word was brought that many bastions had been stormed and the ramparts scaled, and that the enemy were attacking on both sides, held his troops under arms, saying that if his colleague needed help he would let him know. [11] His pride found a match in the other's obstinacy, and Sergius, lest he should seem to have required any aid of his rival, preferred defeat at the hands of the enemy to victory gained through a fellow citizen. [12] For a long time the Romans were slaughtered between the two attacking armies; finally they abandoned their works, and a very few escaped into the larger camp, while Sergius himself, with the chief part of his men, kept on to Rome. It was there decided, on his throwing all the blame upon his colleague, to summon Verginius from camp, and in the meanwhile put lieutenants in command of it. [13] The affair was then debated in the senate and the colleagues heaped abuse on one another. There were but few who spoke for the commonwealth: most of them argued for one or the other disputant, according as each was swayed by private interest or favour.