Plutarch, Life of Caesar 49
Plutarch, Life of Caesar in Plutarch’s Lives, trans. B. Perrin (1919) Cambridge, MA and London, Harvard University Press [Online]. Available at http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0244%3Achapter%3D49 (Accessed 9 June 2014).
After Caesar had found them out, he set a guard about the banqueting-hall, and put Potheinus to death; Achillas, however, escaped to his camp, and raised about Caesar a war grievous and difficult for one who was defending himself with so few followers against so large a city and army. In this war, to begin with, Caesar encountered the peril of being shut off from water, since the canals were dammed up by the enemy; in the second place, when the enemy tried to cut off his fleet, he was forced to repel the danger by using fire, and this spread from the dockyards and destroyed the great library.