The Balkan, or Mount Hæmus, as it was then called, formed the great northern frontier of Macedon and Thrace. From the summits of the range, looking northward, the eye surveyed a vast extent of land, constituting one of the most extensive and fertile valleys on the globe. It was the valley of the Danube. It was inhabited, in those days, by rude tribes whom the Greeks and Romans always designated as barbarians. They were, at any rate, wild and warlike, and, as they had not the art of writing, they have left us no records of their institutions or their history. We know nothing of them, or of the other half-civilized nations that occupied the central parts of Europe in those days, except what their inveterate and perpetual enemies have thought fit to tell us. According to their story, these countries were filled with nations and tribes of a wild and half-savage character, who could be kept in check only by the most vigorous exertion of military power.

      Soon after Alexander's return into Macedon, he learned that there were symptoms of revolt among these nations. Philip had subdued them, and established the kind of peace which the Greeks and Romans were accustomed to enforce upon their neighbors. But now, as they had heard that Philip, who had been so terrible a warrior, was no more, and that his son, scarcely out of his teens, had succeeded to the throne, they thought a suitable occasion had arrived to try their strength. Alexander made immediate arrangements for moving northward with his army to settle this question.

      He conducted his forces through a part of Thrace without meeting with any serious resistance, and approached the mountains. The soldiers looked upon the rugged precipices and lofty summits before them with awe. These northern mountains were the seat and throne, in the imaginations of the Greeks and Romans, of old Boreas, the hoary god of the north wind. They conceived of him as dwelling among those cold and stormy summits, and making excursions in winter, carrying with him his vast stores of frost and snow, over the southern valleys and plains. He had wings, a long beard, and white locks, all powdered with flakes of snow. Instead of feet, his body terminated in tails of serpents, which, as he flew along, lashed the air, writhing from under his robes. He was violent and impetuous in temper, rejoicing in the devastation of winter, and in all the sublime phenomena of tempests, cold, and snow. The Greek conception of Boreas made an impression upon the human mind that twenty centuries have not been able to efface. The north wind of winter is personified as Boreas to the present day in the literature of every nation of the Western world.

      The Thracian forces had assembled in the defiles, with other troops from the northern countries, to arrest Alexander's march, and he had some difficulty in repelling them. They had got, it is said, some sort of loaded wagons upon the summit of an ascent, in the pass of the mountains, up which Alexander's forces would have to march. These wagons were to be run down upon them as they ascended. Alexander ordered his men to advance, notwithstanding this danger. He directed them, where it was practicable, to open to one side and the other, and allow the descending wagon to pass through. When this could not be done, they were to fall down upon the ground when they saw this strange military engine coming, and locking their shields together over their heads, allow the wagon to roll on over them, bracing up energetically against its weight. Notwithstanding these precautions, and the prodigious muscular power with which they were carried into effect, some of the men were crushed. The great body of the army was, however, unharmed; as soon as the force of the wagons was spent, they rushed up the ascent, and attacked their enemies with their pikes. The barbarians fled in all directions, terrified at the force and invulnerability of men whom loaded wagons, rolling over their bodies down a steep descent, could not kill.

      Alexander advanced from one conquest like this to another, moving toward the northward and eastward after he had crossed the mountains, until at length he approached the mouths of the Danube. Here one of the great chieftains of the barbarian tribes had taken up his position, with his family and court, and a principal part of his army, upon an island called Peucé, which may be seen upon the map at the beginning of this chapter. This island divided the current of the stream, and Alexander, in attempting to attack it, found that it would be best to endeavor to effect a landing upon the upper point of it.

      To make this attempt, he collected all the boats and vessels which he could obtain, and embarked his troops in them above, directing them to fall down with the current, and to land upon the island. This plan, however, did not succeed very well; the current was too rapid for the proper management of the boats. The shores, too, were lined with the forces of the enemy, who discharged showers of spears and arrows at the men, and pushed off the boats when they attempted to land. Alexander at length gave up the attempt, and concluded to leave the island, and to cross the river itself further above, and thus carry the war into the very heart of the country.

      It is a serious undertaking to get a great body of men and horses across a broad and rapid river, when the people of the country have done all in their power to remove or destroy all possible means of transit, and when hostile bands are on the opposite bank, to embarrass and impede the operations by every mode in their power. Alexander, however, advanced to the undertaking with great resolution. To cross the Danube especially, with a military force, was, in those days, in the estimation of the Greeks and Romans, a very great exploit. The river was so distant, so broad and rapid, and its banks were bordered and defended by such ferocious foes, that to cross its eddying tide, and penetrate into the unknown and unexplored regions beyond, leaving the broad, and deep, and rapid stream to cut off the hopes of retreat, implied the possession of extreme self-reliance, courage, and decision.

      Alexander collected all the canoes and boats which he could obtain up and down the river. He built large rafts, attaching to them the skins of beasts sewed together and inflated, to give them buoyancy. When all was ready, they began the transportation of the army in the night, in a place where the enemy had not expected that the attempt would have been made. There were a thousand horses, with their riders, and four thousand foot soldiers, to be conveyed across. It is customary, in such cases, to swim the horses over, leading them by lines, the ends of which are held by men in boats. The men themselves, with all the arms, ammunition, and baggage, had to be carried over in the boats or upon the rafts. Before morning the whole was accomplished.

      The army landed in a field of grain. This circumstance, which is casually mentioned by historians,