Titus Livius (Livy), The History of Rome, Book 21
D. Spillan, A.M., M.D., Cyrus Evans, Ed.

54. Between the armies was a rivulet, bordered on each side with very high banks, and covered around with marshy plants, and with the brushwood and brambles with which uncultivated places are generally overspread; and when, riding around it, he had, with his own eyes, thoroughly reconnoitred a place which was sufficient to afford a covert even for cavalry, he said to Mago his brother: “This will be the place which you must occupy. [2] Choose out of all the infantry and cavalry a hundred men of each, with whom come to me at the first watch. Now is the time to refresh their bodies.” The council was thus dismissed, and in a little time Mago came forward with his chosen men. [3] “I see,” said Hannibal, “the strength of the men; but that you may be strong not only in resolution, but also in number, pick out each from the troops and companies nine men like yourselves: Mago will show you the place where you are to lie in ambush. You will have an enemy who is blind to these arts of war.” [4] A thousand horse and a thousand foot, under the command of Mago, having been thus sent off, Hannibal orders the Numidian cavalry to ride up, after crossing the river Trebia by break of day, to the gates of the enemy, and to draw them out to a battle by discharging their javelins at the guards; and then, when the fight was commenced, by retiring slowly to decoy them across the river. [5] These instructions were given to the Numidians: to the other leaders of the infantry and cavalry it was commanded that they should order all their men to dine; and then, under arms and with their horses equipped, to await the signal. [6] Sempronius, eager for the contest, led out, on the first tumult raised by the Numidians, all the cavalry, being full of confidence in that part of the forces; then six thousand infantry, and lastly all his army, to the place already determined in his plan. [7] It happened to be the winter season and a snowy day, in the region which lies between the Alps and the Apennine, and excessively cold [p. 754]by the proximity of rivers and marshes: [8] besides, there was no heat in the bodies of the men and horses thus hastily led out without having first taken food, or employed any means to keep off the cold; and the nearer they approached to the blasts from the river, a keener degree of cold blew upon them. [9] But when, in pursuit of the flying Numidians, they entered the water, (and it was swollen by rain in the night as high as their breasts,) then in truth the bodies of all, on landing, were so benumbed, that they were scarcely able to hold their arms; and as the day advanced they began to grow faint, both from fatigue and hunger.