The men were protected by large shields, which, when the phalanx was formed in close array, just touched each other, and formed an impregnable defense. In a word, the phalanx, as it moved slowly over the plain, presented the appearance of a vast monster, covered with scales, and bristling with points of steel--a sort of military porcupine, which nothing could approach or in any way injure. Missiles thrown toward it were intercepted by the shields, and fell harmless to the ground. Darts, arrows, javelins, and every other weapon which could be projected from a distance, were equally ineffectual, and no one could come near enough to men thus protected to strike at them with the sword. Even cavalry were utterly powerless in attacking such _chevaux de frise_ as the phalanx presented. No charge, however furious, could break its serrated ranks; an onset upon it could only end in impaling the men and the horses that made it together on the points of the innumerable spears. To form a phalanx, and to maneuver it successfully, required a special training, both on the part of the officers and men, and in the Macedonian armies the system was carried to very high perfection. When foreign auxiliaries, however, served under Macedonian generals, they were not generally formed in this way, but were allowed to fight under their own leaders, and in the accustomed manner of their respective nations. The army of Antigonus, accordingly, as he was retiring before Pyrrhus, consisted of two portions. The phalanx was in advance, and large bodies of Gauls, armed and arrayed in their usual manner, were in the rear. Of course, Pyrrhus, as he came up with this force in the ravine or valley, encountered the Gauls first. Their lines, it would seem, filled up the whole valley at the place where Pyrrhus overtook them, so that, at the outset of the contest, Pyrrhus had them only to engage. There was not space sufficient for the phalanx to come to their aid. Besides the phalanx and the bodies of Gauls, there was a troop of elephants in Antigonus's army. Their position, as it would seem, was between the phalanx and the Gauls. This being the state of things, and Pyrrhus coming up to the attack in the rear, would, of course, encounter first the Gauls, then the elephants, and, lastly, the most formidable of all, the phalanx itself.