Titus Livius (Livy), The History of Rome, Book 5
Rev. Canon Roberts, Ed.

21. An enormous crowd went and filled the camp. After the Dictator had taken the auspices and issued orders for the soldiers to arm for battle, he uttered this prayer: [2] ‘Pythian Apollo, guided and inspired by thy will I go forth to destroy the city of Veii, and a tenth part of its spoils I devote to thee. [3] Thee too, Queen Juno, who now dwellest in Veii, I beseech, that thou wouldst follow us, after our victory, to the City which is ours and which will soon be thine, where a temple worthy of thy majesty will receive thee.’ [4] After this prayer, finding himself superior in numbers, he attacked the city on all sides, to distract the enemies' attention from the impending danger of the mine. [5] The Veientines, all unconscious that their doom had already been sealed by their own prophets and by oracles in foreign lands, that some of the gods had already been invited to their share in the spoils, whilst others, called upon in prayer to leave their city, were looking to new abodes in the temples of their foes; [6] all unconscious that they were spending their last day, without the slightest suspicion that their walls had been undermined and their citadel already filled with the enemy, hurried with [7??] their weapons to the walls, each as best he could, wondering what had happened to make the Romans, after never stirring from their lines for so many days, now run recklessly up to the walls as though struck with sudden [8??] frenzy.

At this point a tale is introduced to the effect that whilst the king of the Veientines was offering sacrifice, the soothsayer announced that victory would be granted to him who had cut out the sacrificial parts of the victim. His words were heard by the soldiers in the mine, they burst through, seized the parts and carried them to the Dictator. [9] But in questions of such remote antiquity I should count it sufficient if what bears the stamp of probability be taken as true. [10] Statements like this, which are more fitted to adorn a stage which delights in the marvellous than to inspire belief, it is not worth while either to affirm or deny.

The mine, which was now full of picked soldiers, suddenly discharged its armed force in the temple of Juno, which was inside the citadel of Veii. Some attacked the enemy on the walls from behind, others forced back the bars of the gates, others again set fire to the houses from which stones and tiles were being hurled by women and slaves. [11] Everything resounded with the confused noise of terrifying threats and shrieks of despairing anguish blended with the wailing of women and children. [12] In a very short time the defenders were driven from the walls and the city gates flung open. [13] Some rushed in in close order, others scaled the deserted walls; the city was filled with Romans; fighting went on everywhere. At length, after great carnage, the fighting slackened, and the Dictator ordered the heralds to proclaim that the unarmed were to be spared. [14] That put a stop to the bloodshed, those who were unarmed began to surrender, and the soldiers dispersed with the Dictator's permission in quest of booty. [15] This far surpassed all expectation both in its amount and its value, and when the Dictator saw it before him he is reported to have raised his hands to heaven and prayed that if any of the gods deemed the good fortune which had befallen him and the Romans to be too great, the jealousy which it caused might be allayed by such a calamity as would be least injurious to him and to Rome. [16] The tradition runs that whilst he was turning round during this devotion he stumbled and fell. To those who judged after the event it appeared as if that omen pointed to Camillus' own condemnation and the subsequent capture of Rome which occurred a few years [17??] later.

That day was spent in the massacre of the enemy and the sack of the city with its enormous wealth.