The remaining summer months were spent peacefully in the Hindu Kush, a relaxation for the men who would otherwise have entered India in appalling heat, and a useful time for reconnaissance and the training of the new units. For the past two years the rajah Sasigupta had been maintained in camp, a man 'who had fled from India to Bessus, but now proved trustworthy to the Macedonians'. In the absence of any maps, he was an invaluable source of native information; in early autumn Alexander left Alexandria-in-the-Caucasus and came sharply down from the foothills of the Hindu Kush till he struck the river Laghman and could survey the panorama of the Punjab spread before him. On the far bank of the Laghman, he fortified a native village and gave it the confident name of Nicaea, city of Victory, the theme which he always emphasized. Then, sending a herald east down the long-used road by the river Kabul, he invited the rajahs of the valley to a conference, no doubt on Sasigupta's advice. It was early October before they arrived; meanwhile Alexander had declared the campaign open by a sacrifice, again to the goddess Athena of Victory.

His insistence on victory was not unfounded. He was bringing a professionally led army, complete with catapults, borers and siege-towers, into an independent world of border tribes, numerous but always at variance. Indian cavalry were not to be compared with squadrons of Companions and Iranians; the yantras of their epic heroes were only elementary slings and catapults. Their iron and steel and archery were famous, but they had none of the discipline of the Shield Bearers. The kings in the valleys still trusted in chariots, a force that meant little to the Macedonians of Gaugamela. There was one danger, and Alexander knew it to be very real: at the first news of invasion, Punjab rajahs would send for their mahouts, meaning to fight like their forefathers, trunk and tusk from the backs of the largest known animal species in the world. In India, Alexander was to be the first western general to do serious battle with Elephas maximus , 'nature's masterpiece, the only harmless great thing': catapults were as nothing to the menace of an elephant on musth.

The elephant so dominated the Indian imagination that in Hindu mythology, it was said to support the world on its shoulders. But within five years, Alexander had made it his own: elephants guarded his tent, and their images adorned his funeral chariot, while shortly after his death, his close friend Ptolemy depicted him on Egyptian coins as if dressed in a cap of elephant-skin. As a result the elephant became a symbol of grand pretensions in the west; Caesar would take one to Britain, Claudius would take two: Pompey would try to enter Rome in a triumphal chariot pulled by elephants, only to find that the city gate was too narrow and he had to dismount. Thanks to Alexander a more exact knowledge of the elephant first spread to the west: in his great works on natural history, Aristotle described one with an accuracy that could only have come from dissection, while he also knew how to cure its insomnia, wounds or upset stomach, and how much wheat or wine was needed to keep it in prime condition. But like Alexander's officers, he was inclined to believe that an elephant lived for two hundred years. Through Alexander's army, the skills of elephant and native mahout first raced westwards back to Greece. The use of the howdah, or turreted scat on the elephant's back, became popular, and as neither art nor reliable literature mention it as native to India, the howdah may be an invention of Greek engineers. Within three years of Alexander's death his officers had made elephants fell trees, hold up a river's current and flatten a city wall. They were adorned, as in India, with bells and scarlet coverlets and again as in India, they served as executioners. And yet before him, they had never been seen in the uncongenial landscape of Greece. On the battlefield, their first shock proved decisive, though defenders soon learnt the value of planks of upturned nails against their tender feet: ditches were dug, and momentarily, the elephants halted, as they cannot jump. But when defences seemed to be winning, the Ptolemies shipped hunters to comb the forests of Ethiopia for new and braver recruits, while Carthage, gathering strength, began to explore her western marches for a suitable retort. Hannibal found them, and used them to terrify Italy; Rome, quick to learn, returned the compliment to Macedon and sent envoys cast to the Syrian mud-parks of the Seleucids, with secret orders to hamstring every elephant in sight. Two years later, the Seleucid empire collapsed.

As enemies receded the Romans turned the elephant to show. They would dance, play the cymbals and walk a tight-rope in the circus, and for two hundred years, the audience loved what Alexander had first made possible. But it was the elephant who trumpeted last and loudest: in the mid-fourth century, as Persian power revived, hundreds of elephants tramped west through Asia in the dreaded name of Shapur, 'most monstrous and horrific', wrote a Roman witness, 'of all war's units'.

With the fall of the Western Empire, the elephant vanished from Europe, except for an occasional item of gifts; for six hundred years, however, it had symbolized the open frontier between East and West, a frontier which Alexander had been the first man to roll back. It was, perhaps, his most lasting contribution to classical life.

Without his Indian invasion, the elephant would surely never have been enrolled for Mediterranean military service. Its capture is hazardous and its disadvantages are serious. It dislikes winter cold and is happiest in warm mud; it must eat twice as much as it needs because of poor digestion, consuming 100 pounds of hay and up to fifty gallons of water daily: Aristotle knew of an elephant which would drink 140 gallons between dawn and dusk and then begin again at nightfall. Its hearing is superb but its sight dismally poor; it can swim but not jump, and its transport powers are unremarkable; it moves at a steady six miles an hour, charging rarely and then only for brief bursts at twenty m.p.h. It does not usually breed in captivity, though males spend awkward months on musth , exuding a fluid from their temples which makes them too morose to be controlled. Worst of all, the elephant has no team spirit. Though it is deeply affectionate to its master and mild to small children, human wars mean nothing and it will run amok among friend and foe alike. The most notable elephant in Greek history, called Victor, had long served in Pyrrhus's army, but on seeing its mahout dead before the city walls, it rushed to retrieve him: hoisting him defiantly on his tusks, it took wild and indiscriminate revenge for the man it loved, trampling more of its supporters than its enemies in the process. In war, such devotion was a very mixed blessing.

Men, however, did their utmost to embolden it. In India, it was goaded, equipped with bells and fed on wine: in Ceylon, it was made to take opium. It was encouraged to whisk attackers in its trunk, at least until they wore the deterrent of spiked armour. Its tusks were strengthened with long steel daggers, tipped with poison; its body was protected in iron chain-mail, while seven or more warriors shot and speared from its saddled back, even without the protection of the howdah. Most important of all, though afraid of mice which would run up its trunk, it scared the wits out of horses: at Gaugamela, Alexander's Companion Cavalry had safely outflanked the few opposing elephants, but in the Punjab they would have to withstand hundreds, this time face to face. Alexander was extremely anxious.

His first news in India was that elephants were on his side, for by early October, rajahs from the Indus valley had followed his herald back to the frontier and they promised that their twenty-five specimens were at his disposal. Such a welcome caused Alexander to divide his troops. The main road ran along the banks of the Indus towards the distant town of Taxila, home of the rajah Ambhi who had come, as expected, to surrender. Hephaistion, the mercenaries and half the Companions were to follow him down through the plains of Peshawar and bridge the Indus at Hund where it bends back northwards. In the latter stages, Ambhi would guide and supply them, while on the way they could capture such cities as Pushkalavati, City of the Lotus, in its open fields of sugar-cane and sand; its governor, however, resisted them for a month behind his ditch and mudbrick ramparts, only to be put to death for the trouble. Alexander, meanwhile, had swung far north into the Swat highlands with some 22,000 troops to protect this main road's flank by tactics of terror: it was his lifeline back to Iran, and as a cautious tactician he could not leave northerly tribesmen to cut it when he still hoped for news and reinforcements from Asia. As the native kings had not surrendered, he decided to fight them, not bribe them. Choosing a road far up the river Alishang