Titus Livius (Livy), The History of Rome, Book 23
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

17. Now that Hannibal had lost hope of gaining Nola and had retired to Acerrae, Marcellus at once closed the gates, stationed guards to prevent anyone from leaving, and carried on in the forum an [p. 57]investigation of those who had been in secret¹ conferences with the enemy. [2] Over seventy having been condemned as traitors, he beheaded them and ordered that their possessions should be public property of the Roman people. [3] And setting out with his whole army, after turning over the government to the senate, he pitched camp and established himself above Suessula. [4] The Carthaginian first tried to entice Acerrae into a voluntary surrender; then, seeing them steadfast, prepared to blockade and attack them. But the men of Acerrae had more courage than resources. [5] Accordingly they gave up hope of defending the city, and when they saw that their walls were being encircled, before the enemy's works should be made continuous, they slipped away in the dead of night through the gaps in the earthworks and through neglected guard-posts. [6] Making their way along the roads and where there were none, just as prudence or chance guided the wanderer, they fled for refuge to those cities of Campania of which it was known that they had not changed sides.

[7] After plundering and burning Acerrae, when word had come from Casilinum that the Roman dictator and fresh legions were being summoned, Hannibal led his army to Casilinum, in order to prevent any uprising at Capua also, while the enemy's camp was so near. [8] Casilinum was at that time held by five hundred Praenestines, with a few Romans and Latins, whom the news of the disaster at Cannae had brought thither. [9] As the levy at Praeneste was not completed at the proper date, they had been late in setting out from home, and had reached Casilinum before the news of the defeat. And joined by others, Romans and allies, they set out from Casilinum and, as [p. 59]they were proceeding in a fairly large column, the² report of the battle of Cannae turned them back again to Casilinum. [10] There, being suspected by the Campanians and apprehensive, they spent some days in alternately guarding against plots and hatching them. When credibly informed that the revolt of Capua and Hannibal's entry were being negotiated, they slew townspeople in the night and seized that part of the city which is on this side³ of the Volturnus —for it is divided by that river; and this was the garrison the Romans had at Casilinum. [11] It was joined by a cohort from Perusia, four hundred and sixty men, who had been driven to Casilinum by the same news as the Praenestines a few days before. [12] And there were quite enough men to defend so small a walled city, bounded on one side by the river. But the lack of grain made it seem that there were even too many men.