Such concern for obscurities is partly a credit to his publicity, but also, surely, a sign that the theme of vengeance was taken seriously.

Not even the landscape was spared his commemorations. Behind the battlefield stood the hill of Tell Gomel, which the natives called 'hump of the camel'. For the site of a glorious victory that would never do: he renamed it Nikatorion, Mountain of Victory in his own Greek language, and long after the details of his battle had been obscured this name alone would survive. A name with old associations in the East, it would be turned into Syriac and live on as awana Niqator,the post-house of victory, name of a relay station on the highway whose ancestor had been the Persians' Royal Road. The victory indeed had been memorable, but it was not to be the last: a name, given in a moment of exultation, would persist for six hundred years and set a fashion for Pompey and other victorious Romans, but Darius had escaped, a fact which no alleged message from Parmenion could ever conceal. It would need a longer and far harder march before the new master of Asia could call himself its rightful king.

CHAPTER SEVENTEEN

On 2 October Alexander left Darius's camp at Arbela and marched south, keeping the river Tigris on his right and following the Royal Road, which still determined his route. He had lost all hope of catching Darius in the first flush of pursuit, and as before Gaugamela, he would be wise to wait again and see if the Great King would summon one last army to take a stand in open ground. Meanwhile supplies and the prospect of treasure turned him south to Babylon and the promise of well-earned rewards for his troops. He left the battlefield quickly, a decision which flatterers explained by the stench of the enemy dead and the fear of disease from them. The area was also renowned for poisonous vapours of asphalt and before long, he paused to examine them.

At Kirkuk, where the Road branched eastwards, he 'admired a chasm in the ground from which fire streamed continually as if from a spring and he marvelled at the nearby flood of naphtha, prolific enough to form a lake'. To show it off, the natives 'sprinkled the path which led to the royal quarters with a thin covering of the liquid, stood at the top and applied torches to the wet patches: darkness was already beginning to fall. With the speed of thought, the flames shot from one end of the street to the other and kept on burning.' For the first time, the Eternal Fires of Baba Gurgan had been shown to the Greeks, and at the suggestion of an Athenian who attended him in his bath, Alexander allowed a second experiment. At court, there was a boy 'absurdly plain to look at but with a pleasant singing voice'; in order to find out whether naphtha would bum as well as blaze, he volunteered to be soaked in the liquid and set alight. The flames, however, burnt him severely, and could only be dowsed by repeated buckets of water. The boy survived, shocked and scarred, a warning to those who believe that in matters of natural science, the Greeks preferred theory to experiment.

Leaving the Eternal Fires, Alexander sent a courier eastwards to Susa, the next palace on his obvious path, and himself turned off the Royal Road and took the other great highway of history to lead him south to Babylon. Near Tuz-Kharmatu, he noted the local source of bitumen and learnt that it had been used for the building of Babylon's walls; at Opis, he recrossed the Tigris and marched down the canals of its west bank, through farmland so thickly stocked with millet and barley that his army could eat as they pleased. Everywhere, they were greeted by date palms, the glory of Babylon's economy and a source of wood, beer, food and bedding; the Persians had made up a popular song about its uses, all 360 of them, so they said, one for each day of the Babylonian year.

The country he travelled had long served Persia with crops, new estates and a tribute which none of the rest of her empire could rival. It was two hundred years since Babylon had first fallen to the Persian king, and ever since her land had been bled of its marvellous fertility: Iranian tribesmen had left a life in desert and mountain to rob her of acres of farmland, waterways and city housing; only the native business documents can set such a social change in perspective. It was not that Iranians had found Babylonia more congenial than their homes, for the heat was appalling, and five hundred years later a Chinese visitor would still find their successors living in underground houses cooled by ice, a valid comment on what their forebears had suffered. Most had come because they had to; some were more fortunate, living away in the relative cool of the Persian court and running their western estates through native slaves and agents as a tax-free gift from their king, the others were government servants, judges, overseers, collectors of annual taxes, and they had to make homes wherever they worked. Nor were they always Iranians. Among them lived groups of the foreign soldiers whom the king settled on communes of land in return for taxes or military service; Indians, Arabians, Jews and former nomads, they had changed the face of whole areas of Babylon's countryside, until it was through the farms of foreigners and Persian favourites that Alexander was mostly marching on his way to the greatest city in the east.

From the Babylonian plains around him the court and empire had long drawn the surplus on which their proper working depended. East in the heartlands of Iran, farmland is scarce and water has always been revered, but in Babylonia 1,000 talents of silver, 500 eunuchs and a third of the food for the Persians' court had been levied yearly from natives and military colonists: the Great King's ceremonial among his Royal Relations depended on the surplus drained from the mud fiats of Babylonia. The local satrap had once been believed to stable 16,800 horses of his own, excluding those for war, and to maintain a pack of hounds from the revenues of four villages allotted for the purpose. Private dignitaries had benefited no less conspicuously from a land with a long tradition of large royal estates; Parysatis, queen of Darius II, had owned Babylonian villages whose taxes paid for her wardrobe, some financing her shoes, others her girdles, while her vast farms near Babylon were worked by gangs of slaves and administered by her own sword-bearers and judges. Outside the city, a Persian eunuch or a Paphlagonian favourite might rise to a well-treed park and a planting of rare date palms, while his neighbours were fellow expatriates who had given their own Iranian names, like country squires, to their new home farms; a Persian prince could lease through his agents 2,380 sheep and goats in a single day in Babylon and own farmland in no less than six separate districts from Egypt to Persia, all administered by local foresters and bailiffs. It was an aristocratic style of life which few Macedonians, and fewer Greeks, had ever been able to savour.

'In Babylonia,' wrote Theophrastus the botanist from the reports of Alexander's soldiers, 'badly tilled ground yields a fifty-fold crop, well-tilled ground a hundred fold. Tilling means letting the water lie on the soil for as long as possible in order to form silt; there is very little rain, but the dews feed the crops instead. On principle, they cut the growing crops down twice,' a practice that would amaze most farmers on Greek soil, 'and they let their flocks in to graze it a third time; in Babylon, unlike Egypt, there are very few weeds and coarse grass.' In Babylon, therefore, the prizes were high, not least for Alexander himself, as the long shadow of the Persian king loomed over so much of the countryside's richest assets. Not only had he endowed his favourites, but like the kings of Assyria before him, he had taken the fine royal farms for himself; in private sales, a buyer would even ask for a guarantee that none of the land in question belonged to the Persian king. To the king, it was nothing to rent out a single farm for 9,000 bushels of grain, an ox and ten rams a year; he owned and leased granaries, chicken farms complete with a keeper of the king's poultry, town houses, stabling and even the right to fish. Often his broad estates lay on the banks of canals where they flourished from the nearby irrigation, a privilege which might cost a native farmer a quarter of his annual date crop. As for the canals, those arteries of Babylonian life, he owned many of these too and leased them to native firms of free enterprise, who charged a toll for transport and watering, sold off the fishing and covered their costs from the profits. The canals, meanwhile, grew silted, stifling the farming on which Babylonian life depended, and nobody had the will or the equipment to put them to rights.