The Essays, vol 8

["To whom it was a custom, leading along two horses, often in the hottest fight, to leap armed from a tired horse to a fresh one; so active were the men, and the horses so docile."--Livy, xxiii. 29.]

There are many horses trained to help their riders so as to run upon any one, that appears with a drawn sword, to fall both with mouth and heels upon any that front or oppose them: but it often happens that they do more harm to their friends than to their enemies; and, moreover, you cannot loose them from their hold, to reduce them again into order, when they are once engaged and grappled, by which means you remain at the mercy of their quarrel. It happened very ill to Artybius, general of the Persian army, fighting, man to man, with Onesilus, king of Salamis, to be mounted upon a horse trained after this manner, it being the occasion of his death, the squire of Onesilus cleaving the horse down with a scythe betwixt the shoulders as it was reared up upon his master. And wh