It was the spirit which animated the Roman legions, and the discipline to which they were inured, which gave them their irresistible strength. When we remember that they had not our fire-arms, we are surprised at their efficiency, especially in taking strongly fortified cities. Jerusalem was defended by a triple wall, and the most elaborate fortifications, and twenty-four thousand soldiers, beside the aid received from the citizens; and yet it fell in little more than four months before an army of eighty thousand under Titus. How great the science to reduce a place of such strength, in so short a time, without the aid of other artillery than the ancient catapult and battering-ram! Whether the military science of the Romans was superior or inferior to our own, no one can question that it was carried to utmost perfection before the invention of gunpowder. We are only superior in the application of this great invention, especially in artillery. There can be no doubt that a Roman army was superior to a feudal army in the brightest days of chivalry. The world has produced no generals superior to Caesar, Pompey, Sulla, and Marius. No armies ever won greater victories over superior numbers than the Roman, and no armies of their size, ever retained in submission so great an empire, and for so long a time. At no period in the history of the empire were the armies so large as those sustained by France in time of peace. Two hundred thousand legionaries, and as many more auxiliaries, controlled diverse nations and powerful monarchies. The single province of Syria once boasted of a military force equal in the number of soldiers to that wielded by Tiberius. Twenty-five legions made the conquest of the world, and retained that conquest for five hundred years. The self-sustained energy of Caesar in Gaul puts to the blush the efforts of all modern generals, except Frederic II., Marlborough, Napoleon, Wellington, Grant, Sherman, and a few other great geniuses which a warlike age developed; nor is there a better text-book on the art of war than that furnished by Caesar himself in his Commentaries. And the great victories of the Romans over barbarians, over Gauls, over Carthaginians, over Greeks, over Syrians, over Persians, were not the result of a short-lived enthusiasm, like those of Attila and Tamerlane, but extended over a thousand years. The Romans were essentially military in all their tastes and habits. Luxurious senators and nobles showed the greatest courage and skill in the most difficult campaigns. Antony, Caesar, Pompey, and Lucullus were, at home, enervated and luxurious, but, at the head of the legions, were capable of any privation and fatigue. The Roman legion was a most perfect organization, a great mechanical force, and could sustain furious attacks after vigor, patriotism, and public spirit had fled. For three hundred years a vast empire was sustained by mechanism alone. [Sidenote: The Roman Legion.] [Sidenote: Its composition.]