The Macedonians had advanced with their right leaning on the river. Despite the elephants, Alexander must use his horse, if he expected to win. In this arm he outnumbered the enemy. He could not attack in front, nor, indeed, await the onset of the elephants and chariots. With the instinct of genius, and confident that his army could manœuvre with thrice the rapidity of Porus, as well as himself think and act still more quickly, he determined to attack the Indian left in force. He despatched Coenus with a body of heavy horse by a circuit against the enemy’s right, with instructions, if Porus’ cavalry of that wing should be sent to the assistance of the left, to charge in on the naked flank and rear of the Indian infantry. He himself with the bulk and flower of the horse, sustained by the more slowly moving phalanx, made an oblique movement towards Porus’ left. The Indian king at first supposed that Alexander was merely uncovering his infantry, to permit it to advance to the attack, and as such an attack would be playing into Porus’ hands, he awaited results. This, again, was Alexander’s salvation. It left him the offensive. Porus had not yet perceived Coenus’ march, the probably rolling ground had hidden it, and he ordered his right-flank cavalry over to sustain that of the left, towards which flank Alexander was moving. The phalanx, once uncovered, Alexander ordered forward, but not to engage until the wings had been attacked, so as to neutralize the elephants and the chariots.
These dispositions gave the Macedonian line the oblique order of Epaminondas, with left refused. Alexander had used the same order at Issus and Arbela. As he rode forward, he pushed out the Daan horse-bowmen to skirmish with the Indian left, while he, in their rear, by a half wheel, could gain ground to the right sufficient to get beyond and about the enemy’s flank, with the heavy squadrons of Hephæstion and Perdiccas. The Indian horse seems to have been misled by what Alexander was doing,—it probably could not understand the Macedonian tactics,—for it was not well in hand, and had advanced out of supporting distance from the infantry.
Meanwhile Coenus had made his circuit of the enemy’s right, and, the Indian cavalry having already moved over towards the left, he fell on the right flank and rear of the Indian infantry and threw it into such confusion that it was kept inactive during the entire battle. Then, completing his gallant ride, and with the true instinct of the beau sabreur, Coenus galloped along Porus’ rear, to join the mêlée already engaged on the left. To oppose Coenus as well as Alexander, the Indian cavalry was forced to make double front. While effecting this, Alexander drove his stoutest charge home upon them. They at once broke and retired upon the elephants, “as to a friendly wall for refuge,” says Arrian.
A number of these beasts were now made to wheel to the left and charge on Alexander’s horse, but this exposed them in flank to the phalanx, which advanced, wounded many of the animals, and killed most of the drivers. Deprived of guidance, the elephants swerved on the phalangites, but they were received with such a shower of darts that in their affright they made about-face upon the Indian infantry, to the great consternation of the latter.
The Indian cavalry, meanwhile, had rallied under the cover of the elephants, and again faced the Macedonians. But the king renewed his charges again and again,—it was a characteristic feat of Alexander’s, from boyhood up, to be able to get numberless successive charges out of his squadrons,—and forced them back under the brutes’ heels. The Macedonian cavalry was itself much disorganized; but Alexander’s white plume waved everywhere, and under his inspiration, Coenus having now joined, there was, despite disorder, no let-up to the pressure, from both fronts at once, on Porus’ harassed horse.
The situation was curious. The Macedonian cavalry, inspired by the tremendous animation of the king, maintained its constant charges. The Indian cavalry was huddled up close to the infantry and elephants. These unwieldy creatures were alternately urged on the phalanx and driven back on Porus’ line. The Macedonian infantry had plenty of elbow-room, and could retire from them and again advance. The Indian infantry had none. But finally the elephants grew discouraged at being between two fires, lifted their trunks with one accord in a trumpeting of terror, and retired out of action, “like ships backing water,” as Arrian picturesquely describes it.
Alexander now saw that the victory was his. But the situation was still delicate; he kept the phalanx in place and continued his charges upon Porus’ left flank with the cavalry. Finally, Porus, who had been in the thickest of the fray, collected forty of the yet unwounded elephants, and charged on the phalanx, leading the van with his own huge, black, war-elephant. But Alexander met this desperate charge with the Macedonian archers, who swarmed around the monsters, wounded some, cut the ham-strings of others, and killed the drivers.
The charge had failed. At this juncture,—his eye was as keen as Napoleon’s for the critical instant,—Alexander ordered forward the phalanx, with protended sarissas and linked shields, while himself led the cavalry round to the Indian rear, and charged in one final effort with the terrible Macedonian shout of victory. The whole Indian army was reduced to an inert, paralyzed mass. It was only individuals who managed to escape.
The battle had lasted eight hours, and had been won against great odds by crisp tactical skill and the most brilliant use of cavalry. The history of war shows no instance of a more superb and effective use of horse. Coenus exhibited, in carrying out the king’s orders, the clean-cut conception of the cavalry general’s duty, and Alexander’s dispositions were masterly throughout. His prudent forethought in leaving behind him a force sufficient to insure his safety in case of disaster in the battle is especially to be noted.
Craterus and the other detachments now came up, and the pursuit was intrusted to them. Of Porus’ army, twenty thousand infantry and three thousand cavalry, including numberless chiefs, were killed, and all the chariots, which had proved useless in the battle, were broken up. The Macedonian killed numbered two hundred horse and seven hundred foot. The wounded were not usually counted, but averaged eight to twelve for one of killed. This left few Macedonians who could not boast a wound.