It is important to realize exactly how he did it. He refused such Median excesses as the royal trousers or sleeved overcoat and he is never known to have worn the rounded tiara or royal headdress. He contented himself with the purple-and-white striped tunic, the girdle and the head-ribbon or diadem which had formerly been worn by the king and by his Royal Relations. Now, the diadem was confined to the king alone and cither worn round his purple Macedonian hat or on occasions wound round his bare head. His Companions were given similar purple hats and cloaks bordered with purple, like the official Wearers of the Purple at the Persian court; they were invited to adorn their horses with ornate Persian harness and saddlery. Henceforward access to Alexander was controlled, as in Persia, by ushers and Staff Bearers, whose chief officer was the Greek Chares from Lesbos, presumably bilingual, who later wrote colourful memoirs. Darius's concubines are also said to have been reinstated, 'three hundred and sixty-five in all', according to the Greeks, who liked to number Persian habits as equal to the days in the Babylonian year which they followed. The concubines are never mentioned again and they are unlikely to have been at hand in the wilds of the Caspian Sea. But sooner or later, no doubt, Alexander did recruit them.

Such a rearrangement was bound to cause comment. 'It was now', wrote his Roman historian, four hundred years later, 'that Alexander gave public rein to his passions and turned his continence and self-control to haughtiness and dissipation.' This well-worn theme entirely missed the point, for Alexander was not even the first Greek king to have worn the diadem or Persian dress. For the past sixty years, the tyrants of Syracuse in Sicily had successively taken it up, not because of any connection with Persia, but because they believed, wrongly, that the Persian king was thought to be a living god, and they too wished to be seen by their dress to represent the god Zeus on earth. These nuances of religion must not be discounted for the casual Greek observer who now saw Alexander in a diadem and knew already how he emphasized his relationship with Zeus. They were not a part of Alexander's purpose: that was political, but nonetheless modest. He had refused the showiest Persian clothing because his officers would resent it, and he only intended to wear the remainder in the presence of Orientals. But by the diadem alone he set a lasting fashion: it would be worn by his Successors, when each laid claim to his Asian heritage, and 150 years after his death it was still being imitated by the distant Greek kings of Bactria, cut off from the West in outer Iran. He himself is said to have called it 'the spoils of victory', but it was also a concession to his new position: as a king, not the agent of Greek revenge, he was bound for the heartland of Iranian tribes and he had assumed for sparing use a part of the costume to which his subjects were accustomed. After three heavy victories, these few Persian customs may seem an irrelevant gesture. But more were to follow, and even these few mattered: when Julius Caesar planned to invade the Parthian empire in Alexander's footsteps, there were those at Rome who wished him, as a fit precaution, to be attired in the diadem and Persian costume before he even entered Asia.

To Alexander's staff these changes told of new ambitions. Alexander had already talked of conquering Asia, but as heirs of Darius, they now saw that Asia would mean the whole Persian empire and that they could not turn back until this much, at least, had been made their own. It would be a hard march, for Alexander had set his heart on two kingdoms, and a detail from his chancellery made this all too clear. Letters, as always, needed his daily attention, but no longer did he head them with the forms of polite greeting, except when writing to Antipater and to Phocion, a trusted Athenian politician; elsewhere, throughout, he used the royal 'we', the title of an absolute monarch. Letters which were bound for Europe he sealed with his former ring, but those which referred to Asia were stamped with the ancient seal of the Persian kings.

Such ambitions would not have developed unless Alexander had tested his ground. Three weeks before, he had been awaiting the rest of his army after Darius's capture near Damghan; he was tired and he had just received news that his brother-in-law, Alexander, King of Epirus, had died in battle in southern Italy. He rested his men for mourning by the road which led to Khavar; for three days they encamped in a fortress which they renamed Hecatompylos, 'city of a hundred gates', because of its position on the local roads. A century later, the fortress had grown to become the earliest capital of the Parthian empire, and though many had searched for its famous site, it was not until 1966 that the disputed measurements of Alexander's own surveyors helped in its rediscovery. Three miles south of the road to the Caspian Gates stand a group of tall mounds at Shah-i-Qumis, thrown into clifflike prominence by the flatness of their arid plain. To the north and west rise the distant peaks of the Elburz mountains, but on all other sides the landscape is bare to a treeless plateau and the salt waste desert of Dasht-i-Kavir. It was here that Alexander assembled his troops and asked them for silence beneath the July sun. In the Hundred-gated city he told his men of their many past victories, of the need to follow up a conquest, of the case with which the East would be theirs. They had seen their crusade end, and already Darius's death had started them talking of home But Alexander made light of such common rumour. He carried his soldiery with him until their exhaustion left them and their ambitions seemed to stretch to the far horizon. Then, having roused their fervour, he paused. There was a hush, the reward of the greatest speeches: like the swell on the sea, came the answering shout of agreement: Lead us; lead us, wherever you will.

CHAPTER TWENTY

By wearing the diadem Alexander had laid claim to the whole of Darius's empire. To earn it, he would have to strike eastwards into the fastnesses of Afghanistan through mountain-passes and steppes of sand. 'In Khorasan', runs the Persian proverb, 'the staging posts of the Royal Road are as endless as the chatter of women,' and ahead lay a world of vast space and slowness where the only bustle was the royal courier on the one Royal Road. There was nothing to be gained from Iran's central basin to the south and south-east of him, as it belonged to the Deserts of Salt and Death and was therefore ignored by roads and settlers. Like every traveller, he would skirt it; so, eastwards from his base in Gurgan he marched across a landscape of infinite Harness, hot, hungry but aware that this was only a preliminary to a world of tribes and barons hitherto unknown to the Greeks.

Short of supplies he had to inarch fast and it was as well that the army was still slimmed of the sections detailed to Hamadan; after four hundred miles he paused at modern Meshed where his Persian Companions explained to the camp surveyors that they now had a choice of two routes. One, the future Silk Road from China, led north-east through hill and desert past the oasis of Mcrv to the province of Bactria, where the rebel Bessus, a murderer of Darius, was reported 'to have worn his tiara upright', a symbol of royalty, 'and proclaimed himself King of Asia' with the help of Persian refugees, nomads and the local nobility. The other, also to Bactria, turned due south from Meshed towards the dunes and prairies of Seistan and then crooked north-eastwards up the Helmand valley, into the heart of the Hindu Kush mountains and so by any one of four high passes down into Bessus's new dominions along the banks of the river Oxus. For the moment, Alexander preferred the first of these two alternatives, halt as long as the southern detour.