Alexander, in his own letters, has given us an account of his war with Porus. He says that two armies were separated by the river Hydaspes, on whose opposite bank Porus continually kept his elephants in order of battle, with their heads towards their enemies, to guard the passage; that he, on the other hand, made every day a great noise and clamor in his camp, to dissipate the apprehensions of the barbarians; that one stormy, dark night he passed the river, at a distance from the place where the enemy lay, into a little island, with part of his foot, and the best of his horse. Here there fell a most violent storm of rain accompanied with lightning and whirlwinds, and although he saw some of his men burnt and dying with the lightning, he nevertheless quitted the island and made over to the other side.
Here, apprehending the multitude of the enemy, and to avoid the shock of their elephants, he divided his forces, and attacked their left wing himself, commanding Coenus to fall upon the right, which was performed with good success. By this means both wings being broken, the enemies fell back in their retreat upon the centre, and crowded in upon their elephants. There rallying, they fought a hand to hand battle, and it was the eighth hour of the day before they were entirely defeated.
Almost all the historians agree in relating that Porus was four cubits and a span high, and that when he was upon his elephant, which was of the largest size, his stature and bulk were so answerable, that he appeared to be proportionably mounted, as a horseman on his horse. This elephant, during the whole battle, gave many singular proofs of sagacity and of particular care of the king, whom as long as he was strong and in a condition to fight, he defended with great courage, repeling those who set upon him; and as soon as he perceived him overpowered with his numerous wounds and the multitude of darts that were thrown at him, to prevent his falling off, he softly knelt down and began to draw out the darts with his proboscis. When Porus was taken prisoner, and Alexander asked him how he expected to be used, he answered, "As a king." And Alexander, accordingly, not only suffered him to govern his own kingdom as satrap under himself, but gave him also the additional territory of various independent tribes whom he subdued.
Some little time after the battle with Porus, Bucephalas died, as most of the authorities state, under cure of his wounds, or as Onesicritus says, of fatigue and age, being thirty years old.
Alexander was no less concerned at his death, than if he had lost an old companion or an intimate friend, and built a city, which he named Bucephalia, in memory of him, on the bank of the river Hydaspes.
Aristobulus tells us that Alexander died of a raging fever, having, in a violent thirst, taken a copious draught of wine, upon which he fell into delirium, and died on the thirtieth day of the month Daesius.
But the journals give the following record. On the eighteenth of the month, he slept in the bathing-room on account of his fever.
The next day he bathed and removed into his chamber, and spent his time in playing at dice with Medius. In the evening he bathed and sacrificed, and ate freely, and had the fever on him through the night. On the twenty-fourth he was much worse, and was carried out of his bed to assist at the sacrifices, and gave order that the general officers should wait within the court, whilst the inferior officers kept watch without doors. On the twenty-fifth he was removed to his palace on the other side the river, where he slept a little, but his fever did not abate, and when the generals came into his chamber, he was speechless, and continued so the following day. The Macedonians, therefore, supposing he was dead, came with great clamors to the gates, and menaced his friends so that they were forced to admit them, and let them all pass through unarmed along by his bedside. The same day Python and Seleucus were despatched to the temple of Serapis to inquire if they should bring Alexander thither, and were answered by the god, that they should not remove him. On the twenty-eighth, in the evening, he died.