In accordance with this view of Pyrrhus's character, we see him changing continually the sphere of his action from one country to another, gaining great victories every where, and evincing in all his operations—in the organizing and assembling of his armies, in his marches, in his encampments, and in the disposition of his troops on the field of battle, and especially in his conduct during the period of actual conflict—the most indomitable energy and the most consummate military skill. But when the was fought and the victory gained, and an occasion supervened requiring a cool and calculating deliberation in the forming of future plans, and a steady adherence to them when formed, the character and resources of Pyrrhus's mind were found woefully wanting. The first summons from any other quarter, inviting him to a field of more immediate excitement and action, was always sufficient to call him away. Thus he changed his field of action successively from Macedon to Italy, from Italy to Sicily, from Sicily back to Italy, and from Italy to Macedon again, perpetually making new beginnings, but nowhere attaining any ends.

His determination to invade Macedon once more, on his return to Epirus from Italy, was prompted, apparently, by the mere accident that the government was unsettled, and that Antigonus was insecure in his possession of the throne. He had no intention, when he first embarked in this scheme, of attempting the conquest of Macedon, but only designed to make a predatory incursion into the country for the purpose of plunder, its defenseless condition affording him, as he thought, a favorable opportunity of doing this. The plea on which he justified this invasion was, that Antigonus was his Ptolemy Ceraunus had made a treaty of alliance with him, and had furnished him with troops for recruiting and re-enforcing his armies in Italy, as has already been stated; but Antigonus, when called upon, had refused to do this. This, of course, gave Pyrrhus ample justification, as he imagined, for his intended incursion into the Macedonian realms.

Besides this, however, there was another justification, namely, that of necessity. Although Pyrrhus had been compelled to withdraw from Italy, he had not returned by any means alone, but had brought quite a large army with him, consisting of many thousands of men, all of whom must now be fed and paid. All the resources of his own kingdom had been wellnigh exhausted by the drafts which he had made upon them to sustain himself in Italy, and it was now necessary, he thought, to embark in some war, as a means of finding employment and subsistence for these troops. He determined, therefore, on every account, to make a foray into Macedon.

Before setting off on his expedition, he contrived to obtain a considerable force from among the Gauls as auxiliaries. Antigonus, also, had Gauls in his service, for they themselves were divided, as it would seem, in respect both to their policy and their leaders, as well as the Macedonians; and Antigonus, taking advantage of their dissensions, had contrived to enlist some portion of them in his cause, while the rest were the more easily, on that very account, induced to join the expedition of Pyrrhus. Things being in this state, Pyrrhus, after completing his preparations, commenced his march, and soon crossed the Macedonian frontier.

As was usually the case with the enterprises which he engaged in, he was, in the outset, very successful. He conquered several cities and towns as he advanced, and soon began to entertain higher views in respect to the object of his expedition than he had at first formed. Instead of merely plundering the frontier, as he had at first intended, he began to think that it would be possible for him to subdue Antigonus entirely, and reannex the whole of Macedon to his dominions. He was well known in Macedon, his former campaigns in that country having brought him very extensively before the people and the army there. He had been a general favorite, too, among them at the time when he had been their ruler; the people admired his personal qualities as a soldier, and had been to compare him with Alexander, whom, in his appearance and manners, and in a certain air of military frankness and generosity which characterized him, he was said strongly to resemble. Pyrrhus now found, as he advanced into the country of Macedonia, that the people were disposed to regard him with the same sentiments of favor which they had formerly entertained for him. Several of the garrisons of the cities joined his standard; and the detachments of troops which Antigonus sent forward to the frontier to check his progress, instead of giving him battle, went over to him in a body and espoused his cause. In a word, Pyrrhus found that, unexpectedly to himself, his expedition, instead of being merely an incursion across the frontiers on a plundering foray, was assuming the character of a regular invasion. In short, the progress that he made was such, that it soon became manifest that to meet Antigonus in one pitched battle, and to gain one victory, was all that was required to complete the conquest of the country.

He accordingly concentrated his forces more and more, strengthened himself by every means in his power, and advanced further and further into the interior of the country. Antigonus to retire, desirous, perhaps, of reaching some ground where he could post himself advantageously. Pyrrhus, acting with his customary energy, soon overtook the enemy. He came up with the rear of Antigonus's army in a narrow defile among the mountains; at least, the place is designated as a narrow defile by the ancient historian who narrates these events, though, from the number of men that were engaged in the action which ensued, as well as from the nature of the action itself, as a historian describes it, it would seem that there must have been a considerable breadth of level ground in the bottom of the gorge.

The main body of Antigonus's troops was the phalanx. The Macedonian phalanx is considered one of the most extraordinary military contrivances of ancient times. The invention of it was ascribed to Philip, the father of Alexander the Great, though it is probable that it was only improved and perfected, and brought into general use, but not really originated by him. The single phalanx was formed of a body of about four thousand men. These men were arranged in a compact form, the whole body consisting of sixteen ranks, and each rank of two hundred and fifty-six men. These men wore each a short sword, to be used in cases of emergency, and were defended by large shields. The main peculiarity, however, of their armor, and the one on which the principal power of the phalanx depended as a military body, was in the immensely long spears which they carried. These spears were generally twenty-one, and sometimes twenty-four feet long. The handles were slender, though strong, and the points were tipped with steel. The spears were not intended to be thrown, but to be held firmly in the hands, and pointed toward the enemy; and they were so long, and the ranks of the men were so close together, that the spears of the fifth rank projected several feet before the men who stood in the front rank. Thus each man in the front rank had five steel-pointed spears projecting to different distances before him, while the men who stood in ranks further behind rested their spears upon the shoulders of those who were before them, so as to elevate the points into the air.

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 fries  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.

Pyrrhus advanced to the attack of the Gauls with the utmost fury, and, though they made a very determined resistance, they were soon overpowered and almost all cut to pieces. The troop of elephants came next. The army of Pyrrhus, flushed with their victory over the Gauls, pressed eagerly on, and soon so the elephants and hemmed them in, that the keepers of them perceived that all hope of resistance was vain. They surrendered without an effort to defend themselves. The phalanx now remained. It had hastily changed its front, and it stood on the defensive. Pyrrhus advanced toward it with his forces, bringing his men up in array in front of the long lines of spears, and paused. The bristling monster remained immovable, evincing no disposition to advance against its enemy, but awaiting, apparently, an attack. Pyrrhus rode out in front of his lines and surveyed the body of Macedonians before him. He found that he knew the officers personally, having served with them before in the wars in which he had been engaged in Macedon in former years. He saluted them, calling them by name. They were pleased with being thus remembered and recognized by a personage so renowned. Pyrrhus urged them to abandon Antigonus, who had, as he maintained, no just title to the crown, and whose usurped power he was about to overthrow, and invited them to enter into his service, as the ancient and rightful sovereign of their country. The officers seemed much disposed to listen to these overtures; in fine, they soon decided to accede to them. The phalanx went over to Pyrrhus's side in a body, and Antigonus, being thus deprived of his last remaining support, left the field in company with a few personal followers, and fled for his life.

Of course, Pyrrhus found himself at once in complete possession of the Macedonian kingdom. Antigonus did not, indeed, entirely give up the contest. He retreated toward the coast, where he contrived to hold possession, for a time, of a few maritime towns; but his power as King of Macedon was gone. Some few of the interior cities attempted, for a time, to resist Pyrrhus's rule, but he soon overpowered them. Some of the cities that he thus conquered he garrisoned with Gauls.

Of course, after such a revolution as this, a great deal was required to be done to settle the affairs of the government on their new footing, and to make the kingdom secure in the hands of the conqueror; but no one in the least degree acquainted with the character and tendencies of Pyrrhus's mind could expect that he would be at all disposed to attend to these duties. He had neither the sagacity to plan nor the steadiness of purpose to execute such measures. He could conquer, but that was all. To secure the results of his conquests was utterly beyond his power.

In fact, far from making such a use of his power as to strengthen his position, and establish a permanent and settled government, he so administered the affairs of state, or, rather, he so neglected them, that very soon an extended discontent and disaffection began to prevail. The Gauls, whom he had left as garrisons in the conquered cities, governed them in so arbitrary a manner, and plundered them so recklessly, as to produce extreme irritation among the people. They complained earnestly to Pyrrhus. Pyrrhus paid little attention to their representations. To fight a battle with an open enemy on the field was always a pleasure to him; but to meet and grapple with difficulties of this kind——to hear complaints, and listen to evidence, and discuss and consider remedies, was all weariness and toil to him.

What he would have done, and what would have been the end of his administration in Macedon, had he been left to himself, can not now be known; for, very fortunately, as he deemed it, he was suddenly relieved of all the embarrassment in which he was gradually getting involved, as he had often been relieved in similar circumstances before, by an invitation which came to him just at this time to embark in a new military enterprise, which would draw him away from the country altogether. It is scarcely necessary to say that Pyrrhus accepted the invitation with the most eager alacrity. The circumstances of the case will be explained in the next chapter.