The equality which Titus Livius declares to have prevailed in these two armies, arose from this, that having long served together they used the same language, discipline, and arms; that in disposing their men for battle they followed the same system; and that the divisions and officers of their armies bore the same names. It was necessary, therefore, that as they were of equal strength and valour, something extraordinary should take place to render the courage of the one army more stubborn and unflinching than that of the other, it being on this stubbornness, as I have already said, that victory depends. For while this temper is maintained in the minds of the combatants they will never turn their backs on their foe. And that it might endure longer in the minds of the Romans than of the Latins, partly chance, and partly the valour of the consuls caused it to fall out that Torquatus slew his son, and Decius died by his own hand. In pointing out this equality of strength, Titus Livius takes occasion to explain the whole system followed by the Romans in the ordering of their armies and in disposing them for battle; and as he has treated the subject at length, I need not go over the same ground, and shall touch only on what I judge in it most to deserve attention, but, being overlooked by all the captains of our times, has led to disorder in many armies and in many battles. From this passage of Titus Livius, then, we learn that the Roman army had three principal divisions, or battalions as we might now call them, of which they named the first _hastati_, the second _principes_, and the third _triarii_, to each of which cavalry were attached. In arraying an army for battle they set the _hastati_ in front. Directly behind them, in the second rank, they placed the _principes_; and in the third rank of the same column, the _triarii_. The cavalry of each of these three divisions they disposed to the right and left of the division to which it belonged; and to these companies of horse, from their form and position, they gave the name wings (_alæ_), from their appearing like the two wings of the main body of the army. The first division, the _hastati_, which was in front, they drew up in close order to enable it to withstand and repulse the enemy. The second division, the _principes_, since it was not to be engaged from the beginning, but was meant to succour the first in case that were driven in, was not formed in close order but kept in open file, so that it might receive the other into its ranks whenever it was broken and forced to retire. The third division, that, namely, of the _triarii_, had its ranks still more open than those of the second, so that, if occasion required, it might receive the first two divisions of the _hastati_ and _principes_. These divisions, therefore, being drawn up in this order, the engagement began, and if the _hastati_ were overpowered and driven back, they retired within the loose ranks of the