Both Companions and Foot Companions were troops for open ground and weather. The Companions' horses, like all ancient cavalry, had no nailed horseshoes, and the leather boots which were slipped over their feet in icy conditions soon wore as thin as the hoof itself. But rough ground abounded in Greece, Thrace and Asia, and Philip was too varied a planner not to have taken lameness, broken ranks and the impossibility of charges into account; from three different units he developed a skirmishing force who could also fight in the front line. No troops worked harder or more often. From an early date, he hired archers from Crete, the celebrated home of Greek archery; slingers from Rhodes were added to them, and their sling-stones have been found in the ruins of one of Philip's sacked cities inscribed with suitably rude messages. The crack troops were the 3,000 infantry whom Philip had developed as king's men and given the name of Royal Shield-bearers, formerly confined to the king's grooms and bodyguards. The finest foot force in antiquity, they deserve the credit which is given too often to the men with the sarissas.

The Shield Bearers were troops with two functions. Because the Foot Companions wore their small shields on their left shoulders, their right flank would have been exposed if the Shield-bearer had not been stationed on it and ordered to guard it tightly with the broad circular shields from which they took their name. They served, then, as part of the Foot Companion's block, linking them to the wing of horsemen. From carvings, it seems that as front line troops they wore crested helmets, metal greaves and breastplates and fought with swords and, presumably, spears. But they also served as shock troops on night raids, hill climbs and forced marches of more than thirty miles a day, and the clear evidence of the histories confirms that they were lighter and faster than the Foot Companions; they had no sarissas, of course, and they probably left their heavy shields and body armour behind when detailed to do the work of commandos. As dual-purpose troops, their fitness was amazing. When many of them were over sixty years old, they could still cover thirty miles through desert in one summer's day; they were first up the ladders into besieged cities, or mountain forts in the Hindu Kush, first to savage the elephants and ruin the Persians' scythed chariots. After Alexander's death, they returned from the road to retirement and decided his Successors' grandest battles by showing improvised Foot Companions how their lines could be hacked apart by men old enough to be their grandfathers; they were drilled for war and nothing else, and they loved it.

Archers and slingers for long-range provocation; arrow-shooting catapults for cover and the clearing of city walls; Companions for piercing charges; Foot Companions for routing broken infantry; Shield Bearers for tough missions and for locking the sarissas and cavalry into a solid and well-flanked battle front; Philip had trained the first balanced standing army in the Balkans, and he could add to it his foreign subjects, whether the heavy Thessalian cavalry in their diamond-shaped formations, the light-armed horsemen and javelin-throwers of the Thracian tribes, or the hired Greek infantry who served against their fellow-Greeks without any show of reluctance. But balance was pointless without the freedom to campaign on demand, and here was the last, though not the least, of Philip's innovations.

In the Greek states armies were mostly conscripted from citizens as and when they were needed, and because the citizens were also farmers the army could not go to war in the months of the harvest. Only in Sparta, where a thousand aristocrats had ended by tyrannizing a massive body of Greek serfs, was there enough farm labour to back a standing army; by conquest and plunder, Philip had raised Macedonia to the situation of a Sparta. Too much has been made of the apparent leap in Macedonia's birth rate between Philip's accession and Alexander's death. The figures are misleading and are also influenced by the kingdom's widening boundaries and the recruitment, perhaps, of new tribes and classes; the raw imports of prisoners are far more relevant, as all prisoners who were not sold were enslaved as usual and in an agricultural and unmechanized world where leisure was otherwise impossible Greece's talent for literature, direct democracy and citizen-warfare had always depended on the exploitation of slave labour. Philip had dragged home slaves by the 10,000 to work his mines and farm his feudal nobility's estates. Some, as Athenian visitors to Pella noticed, were given away in droves as presents; others, fellow-Athenians even, were despatched to Philip's own vineyards. Their general effect had been to free Macedonian soldiery from the bonds of the farmers' and foresters' calendar.

'He does not distinguish,' complained one of Philip's enemies, 'between summer and winter; he sets no time of the year aside for inactivity.' Philip's army was not only balanced, it was also backed by enough slaves to make it mobile. In late autumn, Alexander had hurried it through Greece; the following spring, in the month of the harvest, he would direct it up to the Danube, across to Illyria, south again for vengeance in Greece on a march as brisk and varied as any of his father's. The army had only lacked one element, a leader of natural genius; at the age of twenty-one, Alexander would show that his invincibility might, after all, be a theme of substance.

CHAPTER FIVE

If Greece seemed submissive, there were still old scores to be settled in Philip's legacy among the barbarian kingdoms of the European north. Philip had played one Thracian king against another beyond Macedonia's north-east borders and settled an impressive network of new towns through modem Bulgaria as far north as the river Danube and the Black Sea. He had controlled most of the huge rough hinterland of his road to Asia and enjoyed the rich rewards of its royal tithes. It had been the most brilliant of his conquests, but it was not complete: three autumns before his death, Philip had been returning from a conquest on the banks of the Danube with a rich plunder of cattle, girls, small boys and brood mares when the free-spirited tribe of Triballians in Thrace raided his lines, removed all the spoils and wounded him badly in the thigh. The losses were especially annoying as Philip's finances were under strain and his troops were wanting pay; Alexander had served on the march, and he now set out in spring 335 to avenge his father and protect the flanks of the road between Macedonia and the Asian invasion. He knew how lines of communication mattered. Any recovered plunder would be welcomed by the treasury.

For the first time he was very much on his own. Antipater was left in Macedonia and Parmenion was probably in Asia with other proven generals. Alexander had twice had experience of Thracian tribes and landscape; he would now overcome them by an expert use of varied weaponry, the main principle of his military success. All Philip's units were brought into use, except for the Mounted Scouts with their two-handed lances, for they were already in Asia, where the open plains suited them. Only one unit was added as Alexander's own, and though small, it was very significant. During Philip's lifetime, he had privately befriended the King of the Agrianians, a mountain tribe on the upper Strymon river near Macedonia's northern border; a thousand or so of their javelin-throwers now came with their king to join Alexander's skirmishing-troops, and as a foil to Philip's Shield Bearers, they would show most admirable ferocity. The Ghurkhas of Alexander's army, they are the one point at which he already excelled his father's balanced armoury

The march was planned on the model of Philip's expedition four years earlier, and its aims were the Danube and the Triballians, Philip's enemies. Orders were sent for the small fleet of long warships to row from Byzantium, where they were guarding the Dardanelles. They were to hug the shore of the Black Sea northwards to the mouth of the Danube, and then come up river to meet the land army. Only Philip, among Greece's generals, had ever reached the Danube, but Alexander had watched him do it; in emulation of his father, he was already thinking ambitiously, and while attending to the sacrifices which were the business of every general, he chanced on support for his thoughts. While he offered meat to Dionysus in the famous sanctuary of Crestonia in eastern Macedonia beside his road, the flame flared up unusually high, a peculiarity of the shrine, and his prophets were quick to recognize the traditional omen of a victorious king. It was not long before the omen of flame was confirmed on the battlefield.