Titus Livius (Livy), The History of Rome, Book 25
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

39. Beyond the nearest camp and at a distance of six miles from it were other forces of the Carthaginians. Between them there was a deep valley, densely wooded. About the middle of this wood a Roman cohort and cavalry were concealed after the Punic method. [2] The road being thus cut off at the half-way, the rest of the forces were led in a silent column to the nearest enemy. And as there was no outpost before the gates nor sentinels on the earthwork, and no one anywhere opposed them, they made their way into the camp as if it were their own. [3] Then the trumpets sound and a shout is raised. Some slay [p. 491]the enemy half-asleep, some throw firebrands on¹ the dry, thatched huts, some seize the gates, to block escape. [4] As for the enemy, fire, shouting and slaughter, all at once, make them virtually senseless and do not allow them to hear any orders or to look out for themselves. Unharmed they encounter bodies of armed men. [5] Some rush to the gates, others, since the roads are blocked, leap over the earthwork. And everyone who escaped fled at once in the direction of the other camp; [6] whereupon they were surrounded by the cohort and cavalry dashing out of their hiding place and were slain to the last man. [7] Yet, even if a man had escaped from that slaughter, so swiftly did the Romans hasten from the captured nearer camp to the other camp that news of the disaster could not anticipate them. [8] But there, the farther it was from their enemy, and since some had scattered just before daylight to bring in fodder and firewood and booty, the more neglect and disorder did they find everywhere; only stacked arms at the outposts, the soldiers unarmed, either sitting and lying on the ground or strolling outside the wall and the gates. Against these men, so care-free and regardless of order, the Romans, who were still fired by their recent battle and made confident by victory, went into battle. [9] And so no resistance whatever could be offered at the gates. Inside the gates there was a rush from every part of the camp at the first shouting and commotion, and a fierce battle began. [10] It would have lasted long too, had not the sight of the Romans' bloody shields given the Carthaginians evidence of the other disaster and consequently inspired alarm. This terror made them all take to flight, and pouring out wherever a way could be found [p. 493] —except those overtaken by the sword —they lost² possession of the [11] camp. Thus in a night and a day two camps of the enemy were taken by assault under the command of Lucius [12] Marcius. That about thirty-seven thousand of the enemy were slain is the statement of Claudius,³ who translated Acilius' annals out of Greek into the Latin language; that about one thousand eight hundred and thirty were captured and a vast amount of booty [13] taken. And in this he says that there was a silver shield weighing a hundred and thirty-seven pounds, bearing the likeness of Hasdrubal [14] Barca. Valerius of Antium⁴ relates that one camp was captured, that of Mago, and seven thousand of the enemy slain; that in a second battle they sallied out and fought with Hasdrubal; that ten thousand were slain, four thousand three hundred and thirty [15] captured. Piso⁵ states that five thousand men were slain from an ambush, while Mago was pursuing in disorder our retreating [16] men. In all of them great is the name of Marcius the general. And to his real fame they add even marvels: that as he was speaking a flame burst from his head without his knowledge, causing great alarm among the soldiers who stood around [17] him. They say that as a memorial of his victory over the Carthaginians, down to the burning of the Capitol there was in the temple a shield called the Marcian, bearing a likeness of [18] Hasdrubal.⁶ —Thereafter the situation in Spain was quiet for a long time, since both sides, after receiving and inflicting such losses [p. 495]upon each other, hesitated to risk a decisive⁷ engagement.