For the moment, all was working out splendidly. At Byblos he welcomed another absent king's son; at Sidon, a crucial port, past history helped him to a decisive coup. The Persians had suppressed Sidon's bid for independence some twelve years earlier and after the usual savagery had left the city to a tame king. Memories of those heady days when Sidon's citizenry had hacked down the trees in the Persian governor's park had not yet died, and when Alexander could promise the deposition of Persia and her agent, the city was his to treat as he pleased. Some fifty ships manned by Sidon were sailing in the Persians' fleet, and the surrender of their home city would surely persuade them to defect or return peacefully; the choice of a new king is said to have been left to Hephaistion, who picked on a man hitherto employed in a garden. Who better to rule than a gardener, even if the story may reflect an ancient myth in Semitic kingship? Promoted from the flowerbed, King Abdalonymus was as popular a choice with the mass of Sidonians as Alexander intended, and in return, he entertained the Companions to a lion-hunt in his nearby royal game park; scenes from the hunt were carved on his sarcophagus when he died, a Companion himself.

However, friendship with Sidon meant likely trouble at the ancient harbour city of Tyre, for while Sidon had recently suffered from Persia, her rival Tyre had flourished and so lay powerful and forbidding on Alexander's coast route southwards. When Alexander approached, he was met by the city's elders and the son of their absent king with gifts and a golden crown, promising to do whatever Alexander might command. Alexander replied that he wished to pay sacrifice to Melkarth, a Tyrian god whom he identified with his ancestor Heracles: this had been advised by an oracle. He had once watched his father use the same pretext for an unavoidable war and it was shrewdly calculated, for it exposed the Tyrians' offer and revealed that at heart, they wanted to remain neutral. If Alexander wished to sacrifice, there was an adequate temple to Heracles at Old Tyre on the mainland; he was not to enter their new island city. This retort made Alexander angry and within days he had begun to demolish Old Tyre in order to use its stone and timber for an assault on New Tyre's offshore position.

Anger was not his principal motive. Tyre, like Sidon, was one of the home ports for the crews in the Persian fleet and as Alexander had already decided to head south into Egypt, he could not leave it unsubdued on his main route of communication, especially as many of Tyre's warships had remained in the city. On a wider front, the Tyrians had been holding a grand festival in honour of Melkarth, to which representatives had come from Carthage, a city once founded by Tyre; these Carthaginians promised help in the event of a siege. Alexander may not have known of their promises but he would be aware of Carthage's link with Tyre and the possibility of naval help once his back was turned. It might be important to scare off this new threat from the west.

The process was bound to be laborious. New Tyre stood on a walled island two and three-quarter miles in circumference, cut off from the coast by half a mile of sea, shallow at first but soon dropping to a depth of some 600 feet. The city was fitted with two harbours, one on the north and another on the south-east outside the walls, and the wall itself rose as much as 150 feet, at least in the opinion of the besiegers. Though a king of Cyprus had once taken Tyre by force forty years before - a remarkable success about which regrettably little is known - he would have been supported by his strong fleet; in early January, a month of rough seas, Alexander was proposing to assault an island city and its remaining fleet when he had no ships of his own. In the early sixth century, Tyre had withstood siege by Nebuchadnezzar, King of Babylon, for thirteen consecutivc years, and against a land-bound Alexander it must have reckoned that its chances of survival were equally high. Evidently the Macedonian soldiery had their reservations; Alexander was forced to tell them that he had seen Heracles in a dream, extending his right hand and inviting him inside the city, while his favourite prophet Aristander announced cheering interpretations of such omens as blood-dripping rations of bread. In the background there were more solid reasons for confidence, though the historians never explained them.

In antiquity the assault of a walled city already required the combination of men and machines. It is naive to exalt the inventions above men's moods and opinions; Greeks in Alexandria would later discover steam-power but only use it to propel toy engines, and Buddhists were content if their newfound water power would peacefully revolve their prayer-wheels. But on the battlefield, inventions are more readily applied and there they can help to conquer the most soldierly courage. Like men, the inventions have fought a to-and-fro battle of their own. That primitive weapon for smashing, the mace, was first defeated by the helmet; to the helmet, the axe made cutting reply, only to be kept at bay by the newfound bow and arrow. Arrows brought on body armour, body armour diminished the earlier man-sized shield, smaller shields left a hand free for the thrusting-spear, and the discovery of the long-range composite bow in Mesopotamia in the seventeenth century B.C., backed by the mobile platform of the chariot, had been an innovation on the scale of powder and musket. So too with the race between siege technique and city walls. Axes, poles and ladders had menaced third millennium walls of brick and mud, but in the second millennium, walls had improved and regained the upper hand. Battering rams and siege-towers reached their peak in seventh-century Assyria, whereupon walls, shocked and overtopped, grew sloping banks at their base, bastions and recesses in their outlines and often changed their water-soluble bricks to massive thicknesses of stone. Since the heyday of Assyria, siege technique in the east had been exported to the Mediterranean, but until recently, it had not been advanced; city walls had had things more their own way, and there was no uniformity of stone materials or defences among the Greek cities. In 332 Alexander, like King Tiglath-Pileser III of Assyria and his lightly built battering ram, was one step ahead in the battle of weapons; he was patron of a stone-throwing catapult, fitted with washers and powered by springs of twisted sinew.

It is ironic that the walls of Tyre were to be the first fortification to feel the force of boulders from Greek engines. Compared with the kingdoms of the east, the Greeks had been slow to develop advanced siege equipment, drawing their knowledge of siege-towers and rams in the course of the fifth century from their contact with the Orient; probably the techniques had passed from Assyria to Tyre, from Tyre to Carthage, from Carthage to the battlefields of Sicily, where the resident Greeks could have learnt from their Carthaginian enemies. Tyre, then, had been a vital link in the roundabout passage of siegecraft to the Greeks. But the route had also worked in reverse. At the turn of the century. Dionysius I, ruler of Syracuse, had first sponsored an elementary form of arrow-shooting artillery which he then turned against the startled Carthaginians: Carthage no doubt had reported her new wounds to Tyre and hence in 332 the Tyrian engineers had copied Dionysius's idea, and evolved arrow-catapults of their own. But they had not bargained with Philip and the intervening rise of Macedonia. By 340 Greek engineers under Philip's patronage had disovered the powers of a torsion spring; at first they fitted it to the old Sicilian brand of catapult, but soon pupils of Philip's head engineer, Polyeidus the Thessalian, had gone on to experiment with torsion-powered stone-throwers for Alexander's benefit. The old Syracusan catapult, presumably still used at Tyre, was repeat-firing without a torsion spring; whereas its range was some two hundred yards and its weapon a metal-tipped bolt, Alexander's new stone-throwers, improved since their first appearance at Halicarnassus, could rip through the ranks of defenders at 400 yards, and at 150 yards they could damage a city wall. To judge from several stories, the accuracy of ancient artillery was most impressive; when the Spartan king Archidamus was shown an arrow-shooting catapult for the first time, 'By Heracles', he remarked, 'man's courage is now a thing of the past.'