They were certainly aware of their weakness, because Memnon advised against a stand-up battle, suggesting instead that they should retire into the interior, wasting the country as they went, and so hinder the rapidity of the enemy’s march until their own fleet appeared; then the war could be carried into Greece and Alexander forced to retreat. But this prudent strategy was not acceptable to the Persian satraps, who preferred active measures that seemed to offer a chance of preventing Alexander from getting a firm foothold in Persian territory.
They prepared to offer battle by taking up a position on the river Granicus, a stream flowing down from the northern slope of Mt. Ida to the Propontis. It seems as if the Persians, conscious of their weakness, selected a battlefield where their enemies, with a river in front of them, would find it a matter of some difficulty to attack. They may have supposed that Alexander would hesitate to advance under such unfavorable conditions. The Macedonian army was so disposed that the heavy-armed infantry held the center while the wings were formed by the cavalry and the bowmen. Alexander himself was with the picked Macedonian cavalry on the right wing; next him were arranged the hypaspists, extending towards the middle. This wing, comprising cavalry, bowmen, and heavy-armed troops, appears to have crossed the river first and to have put to flight the Persian cavalry. That the Persians used horsemen here and not bowmen seems strange. Cavalry were of little use in preventing an advance up the steep slope from the stream.
First the Persian horse were put to flight by the right Macedonian wing, commanded by Alexander, who took an active part in the hand-to-hand conflict; then the phalanx of Greek mercenaries on the Persian side, who had stood by hitherto without taking any part in the engagement, were attacked in front by the Macedonian phalanx and on the flanks by the cavalry and bowmen and, being thus prevented from making any real resistance, were hewn down or taken prisoners. The Macedonian loss was so small, eighty-five horsemen and thirty foot soldiers, that it would seem that probably the Greek mercenaries, instead of resisting their own kinsmen, allowed themselves to be taken prisoners. The brunt of the battle was borne by the Persian horsemen, who fought valorously, and in the obstinate scrimmage with them Alexander was in considerable personal danger. Two of the satraps lost their lives on the field. The Greek prisoners were sent in chains to Macedon, and of the booty taken, 300 suits of armor were sent to the Parthenon at Athens as a thank-offering, a visible reminder to the Greeks of the victor’s progress. (May-June, 334 B.C.)
The fruits of the victory were immediate: several of the principal cities surrendered, among them Sardis, with its impregnable citadel, and Ephesus. In both places Alexander was greeted as a deliverer from Persian tyranny; democratic government was restored, and a beginning was made for organizing a massacre of the oligarchic faction. This Alexander prevented, making it clear by his intervention that he did not wish to alienate the sympathies of the propertied classes in Asia. Of the other Greek cities in Ionia and Æolis, only one gave serious trouble, Miletus, which looked to the Persian fleet for aid. It was occupied besides by a strong garrison of Greek mercenaries. Alexander’s fleet, however, appeared at Miletus before the Persian fleet, which was on its way from Cyprus and Phœnicia, reached the scene of action. When this fleet came up, it tried in vain to entice the Macedonian ships into an action, and remained idly by while Alexander besieged Miletus and finally took it by storm.
The sole stronghold still left to Persia in the region was Halicarnassus to the south. Hither the Persian fleet repaired, and here, as the place was strongly fortified and well manned with troops, Memnon planned to establish a base for further operations by sea against Greece itself. But Alexander declined to take the risk of meeting the Persian fleet in a naval engagement. Winter was at hand, and most of the Macedonian ships had been sent home; there was only a small squadron left, and the king marched south with his army to besiege Halicarnassus by land.
The problem before him was anything but easy, for Halicarnassus, besides being strongly fortified, had through the presence of the Persian fleet free communication with the outside. It could be supplied with food, although the opportunity of obtaining mercenary troops from Greece was made difficult through the fear of Macedon. The city walls were surrounded with wide ditches and these Alexander filled up, in order to give access to his siege engines. Several breaches were made, but the first attempt to storm the place failed, and the defenders of the city erected new fortifications in place of those that had been cut down. They also made a sortie, trying to destroy the siege engines, but were repulsed with loss. Memnon saw that the town could no longer be held, and by night embarked his troops, carrying them to Cos; but before he left he set fire to the abandoned town. Alexander immediately entered, showed himself merciful to its citizens, and proceeded on his march, leaving a division of 3050 men to watch the citadel of Halicarnassus, which evidently he did not think of sufficient importance to besiege now that the Persians had only a small number of troops in the neighborhood, in Salmakis and on the island Arconnesus.
The whole of the province of Caria now ceased to resist, with the exception of a few places on the coast. A part of the Greek army, under the orders of Parmenio, were sent into winter quarters in Lydia, while Alexander advanced through Lycia and Pamphylia, without meeting any real resistance, and marched by the way of the mountainous country of Pisidia, among a population never conquered by the Persians, and in the spring of 333 joined Parmenio at Gordion, the ancient capital of Phrygia. From here the route of the army was through Cappadocia by the narrow pass called the Cilician Gate, by which the road from the interior plateau crosses the Taurus on its way to Tarsus. The garrison which occupied the pass fled on the approach of the Greek army, Tarsus itself was abandoned, and the whole province of Cilicia was occupied without resistance.
In the meantime, however, Memnon had not been inactive, and he was putting to good use his superiority in naval strength. Several islands had either been occupied or were making preparations to join the Persian general, and even in continental Greece the anti-Macedonian influence was being felt. There was no question that Memnon’s arrival on the shores of European Greece would be the signal for a general abandonment of the Macedonian cause. Athens even sent an embassy to Darius, although the city did not dare to join the Persians openly. In the midst of these successes, Memnon was taken ill and died. Those who succeeded him in the command showed none of his capacity. The fleet was kept in inactivity, and though on land some small successes could be put to the credit of the Persian arms in Asia Minor, the soldiers operating there were soon directed to join the main army of Darius in Syria, now being collected to meet the advancing Greeks. When the news of Alexander’s victory at the Granicus reached the interior of the Persian Empire, Darius began to draw together a large army, and leaving Babylon in January, reached northern Syria in autumn. Alexander was still in Cilicia, detained in Tarsus by a severe illness, and on his recovery busied himself with the conquest of some of the coast cities. But when he heard of the advance of Darius, he marched trough the narrow pass near the coast which connects Cilicia and Syria, and commenced the siege of Myriandros, the first Phœnician city on the road. He evidently reckoned on Darius meeting him in the level places of northern Persia, where the latter’s cavalry could be used to its best advantage, but Darius showed a keener strategical instinct than is usually associated with Persian generalship. While Alexander was taking the coast road south, Darius’ army made a northerly movement, passing over a difficult mountain region, and so appeared in the rear of the Macedonian army on the level plain near Issus. The Persians had a strong position; on their right was the sea, and on their left a chain of mountains. On the front they were protected by the deeply worn bed of the river Pinarus. They had also constructed a line of earthworks.
The preliminary operations of the Persians were conducted with great intelligence. By them Alexander was cut off from his base and his position was desperate, unless he could restore his line of communications by a successful engagement. This was no easy matter, for the mountain defile, the Assyrian Gate, had to be passed through, a place where the mountains and the sea are so close that there is room only for a road. Darius had an excellent position but failed to make any use of it. Without attempting to interfere he allowed Alexander to march through the narrow strip of land between the mountains and the sea and to change from a column formation into regular battle array.
It took the Greek commander the whole night to make the journey from Myriandros, a place south of the defile, to the level country on the banks of the Pinarus. As Alexander’s army debouched on the plain, the cavalry and the light-armed troops sent against them by Darius failed to arrest their progress. The Persians were outmanœuvered from the start, for on the plain, which had very narrow limits—a little more than two miles wide—Darius could make no use of his superior numbers, nor was there opportunity for bringing to bear to any purpose the Persian advantage in cavalry. It was possible for Alexander to extend his own line of battle just as far as the enemy could, and the nature of the ground protected him against any enveloping manœuver. Thus the disposable forces, on either side, were equalized, and on account of the superior training and skill of the Macedonians, there was little doubt from the first as to the issue of the fight.