Titus Livius (Livy), The History of Rome, Book 27
Frank Gardner Moore, Professor Emeritus in Columbia University, Ed.

49. More of the elephants were slain by their own drivers¹ than by the enemy. These used to have a carpenter's chisel and a mallet. When the beasts began to grow wild and to dash into their own men, the keeper would place the chisel between the ears, precisely at the joint which connects the neck with the head, and would drive it in with all possible force. [2] That had been found to be the quickest means of death² in a brute of such size, when they got beyond the hope of control. And the first man to introduce the practice had been Hasdrubal, a general who was often notable at other times, but pre-eminently in that battle. [3] It was he that by encouraging them and sharing the same dangers sustained his men in battle; he that fired them, now by entreating, now by upbraiding, the exhausted and those who because of weariness and over-exertion were giving up; he that recalled those who tried to flee and at not a few points revived the battle they were abandoning. [4] Finally, when fortune unquestionably was on the enemy's side, in order not to survive so large an army that had followed his fame, he spurred his horse and [p. 405]charged into a Roman cohort. There, in a manner³ worthy of his father Hamilcar and of Hannibal his brother, he fell fighting.⁴

[5] Never in a single battle of that war were so many of the enemy slain, and a disaster equal to that of Cannae, whether in the loss of the general or that of an army, seemed to have been inflicted in return. [6] Fifty-six thousand⁵ of the enemy were slain, fifty-four hundred captured. Great was the rest of the booty, both of every kind and of gold and silver as [7] well. In addition, Roman citizens —over four thousand of them —who as captives were in the hands of the enemy were recovered. This was some compensation for the soldiers lost in the battle. For the victory was by no means [8] bloodless. About eight thousand Romans and allies were slain, and to such an extent were even the victors sated with bloodshed and slaughter that on the next day, when word was brought to Livius, the consul, that the Cisalpine Gauls and Ligurians, who either had not been present in the battle, or had escaped in the midst of the carnage, were moving away in one column, with no trustworthy guide, no standards, no formation or high command, that they all [9??] could be wiped out, if a single regiment of cavalry should be sent, the consul said, “No! let there be some survivors, to carry the news both of the enemy's disaster and of our valour.”⁶

[p. 407]