On the Greek side the left wing was commanded by Alexander in person, and it was made up of the Macedonian cavalry, the hypaspists, and a part of the ordinary infantry. The vigor of their onslaught was irresistible, and the Asiatics opposed to them gave way after a short struggle and fled. The whole Persian center was disorganized, even Darius avoiding capture with difficulty. His chariots, his royal robes, and his arms fell into the hands of the victorious Greeks. In another part of the field Parmenio, who was in command of the left wing of the Greek army, had no easy time in withstanding the charges of the Asiatic cavalry, and also when the Macedonian phalanx undertook to storm the heights which were occupied by Greek mercenary troops on the other side, they were repulsed with considerable loss. Fortunately, Alexander, after defeating the division opposed to him, was able to use his infantry to attack the mercenaries on their rear, and they were forced to withdraw from the field. They retired in good order, but the Persian cavalry proved inefficient, and were repulsed with great loss. In their flight they demoralized the reserves which had been placed by the Persians immediately behind the line of battle. The Persian army ceased to exist as a military entity and the fugitives were saved from further pursuit only by the early nightfall of the autumn season. Darius was able to bring together on the other side of the Syrian mountains 4000 men, most of whom were Greek mercenaries, and with a small force he recrossed the Euphrates. The main body of the Greeks, attached to the army of Darius, made their way to Tripolis in Phœnicia and from there sailed to Cyprus. (October, 333 B.C.)

After the battle the Persian camp was occupied by the Greeks, and among the captives were the mother of Darius and his wife, Stateira, and her children. These members of the royal household were treated considerately. Their presence with the Greek army was a most valuable asset, and a few days after his defeat Darius began to open negotiations for the purpose of having the captives restored to him. Alexander showed no unfriendly spirit, and received an embassy with formal proposals of peace from Darius. The conditions were, that all of the country west of the Euphrates should be ceded and the large sum of 10,000 talents given for the return of the royal captives. In addition to this, as a pledge of good faith, it was proposed that Alexander should receive one of the king’s daughters in marriage. The offer was a proof that Darius realized how deep was his humiliation and how small the chance of successful resistance to the conqueror.

Liberal as the terms were, it must have been plain to Alexander that to make peace now was to leave his work half finished, especially as the first half was the more difficult. In it he had defeated the best soldiers under the command of Darius, and there was nothing more to fear from the Persian fleet, its most important units being withdrawn to protect Syria, nor was a rising in Greece likely to be attempted. The news of the battle of Issus had made the anti-Macedonian faction in the Greek cities see the purposelessness of counting on the co-operation of Persia. At the Isthmian games the representatives of the Hellenic confederation voted Alexander a golden crown as a defender of the liberties of Greece.

Alexander answered the proposition of the Persian king in a stern mood, fully conscious of his strength. His letter to Darius, which has been preserved, is a document that speaks in no uncertain tone. “Your ancestors invaded Macedonia and the rest of Greece, and without provocation inflicted wrongs upon us. I was appointed leader of the Greeks and crossed over into Asia for the purpose of avenging those wrongs; for ye were the first aggressors. In the next place ye assisted the people of Perinthus, who were offenders against my father, and Ochus sent a force into Thrace, which was part of our empire. Further, the conspirators who slew my father were suborned by you, as ye yourselves boasted in your letters. Thou with the help of Bagoas didst murder Arses (son of Ochus) and seize the throne unjustly and contrary to the law of the Persians, and then thou didst write improper letters regarding me to the Greeks, to incite them to war against me, and didst send to the Lacedæmonians and other of the Greeks, for the same purpose, sums of money (whereof none of the other cities partook but only the Lacedæmonians); and these emissaries corrupted my friends and tried to dissolve the peace which I had brought about in Greece. Wherefore I marched forth against thee who wert the aggressor in general. I have overcome in battle first thy generals and satraps, and now thyself and thine host, and possess thy land through the grace of the gods. Those who fought on thy side and were not slain but took refuge with me, are under my protection and are glad to be with me and will fight with me henceforward. I am lord of all Asia, and therefore do thou come to me. If thou art afraid of being evilly entreated, send some of thy friends to receive sufficient guaranties. Thou hast only to come to me to ask and receive thy mother and children, and whatsoever else thou mayest desire. And for the future whenever thou sendest, send to me as to the Great King of Asia, and do not write as to an equal, but tell me whatever thy need be, as to one who is lord of all that is thine. Otherwise I shall deal with thee as an offender. But if thou disputest the kingdom, then wait and fight for it again and do not flee; for I will march against thee, wherever thou mayest be.”

Darius now set about collecting another army and made no more peace proposals. He gathered the fragments of the force that had been beaten at Issus, and to this were added contingents drawn from all the furthermost parts of his empire still in his hands. The army so formed was almost exclusively Asiatic, for of Greek mercenaries there were only the soldiers, a few thousand all told, who had followed him in his flight. No others could now be secured. Darius’ new plan was to await the approach of Alexander on the plains of Assyria, where the Persian cavalry could be used with most effect.

On Alexander’s part there was no haste in turning to the interior. Instead of following Darius, he remained on the sea coast, while Parmenio was sent to Damascus with half the Greek army, to seize the treasure left there by Darius before the battle of Issus. Alexander with the rest of the army turned south to the conquest of the great island city of Phœnicia, which unlike its smaller neighbors had refused to surrender and had declared its neutrality to Alexander. Tyre was the center of Persian sea power, and so long as it remained independent its fleet could be used against the Greek king, either on the sea itself or as an instrument for creating disturbances in continental Greece.

The siege of Tyre involved special difficulties; not only were its walls high and strong, but it was situated on an island separated from the mainland by a shallow body of water. As Alexander had no fleet adequate to conduct aggressive operations from the open sea against the city, he planned to bring up his siege engines against the walls from the land side, by building a causeway over the shallow body of water. The defenders of the town tried repeatedly and with great bravery to prevent such an approach from being made. Tyre’s own commercial competitors, Cyprus and the less important Phœnician cities, including Sidon, placed their navies at Alexander’s disposition, and with their ships he began to operate from the sea. The situation of the town was desperate, but its people made a defense as desperate and as resourceful as their daughter city Carthage in later days against the Romans.

When the causeway was finally constructed, the walls on this side, being 150 feet high and enormously thick, were not damaged by the siege engines. Accordingly Alexander changed his plans quickly; the engines were mounted in vessels and a breach was effected in one of the battlements extending along the harbor. While the Macedonians were now able to penetrate the city, they met with heavy resistance from the besieged townsmen, and the occupation of Tyre was only effected by the protection of Alexander’s naval allies, who forced an entrance into the two harbors, and so drew off a portion of the defenders from the side where the Greeks were making their attack. The stubborn defense cost the Tyrians 8000 men, and of the prisoners 3000 were sold as slaves. On the Macedonian side the loss was small, only amounting to 400 men, but no mention is made of the losses of the allied fleets. The siege of Tyre lasted seven months, the city falling in July, 332. The long delay was worth while, for the successful issue showed how invincible was the generalship of the Greek leader. By the possession of the city he held the key to the control of the eastern Mediterranean.

On the way south he met with no resistance except from the strong citadel at Gaza, which withstood him for two months and was finally taken by storm. The march to Egypt could now be safely undertaken, as the whole sea coast from the Hellespont south was in the hands of the Greeks. Egypt itself had no love for its Persian masters. It had not long before been autonomous for fifty years, and it had been brought back under the régime of the Great King under circumstances of repression that made its inhabitants greet Alexander as a liberator. The Persian governor, seeing the folly of resistance, gave up the strong places, and Alexander passed the winter in the country. During his stay he founded the only good harbor on the coast, the city which still bears his name. This undertaking was not the boastful action of a conqueror, solicitous of the praise of posterity; it was a keen-sighted scheme to divert from the Phœnician towns of Syria the control of the Mediterranean trade. Within half a century Alexandria had become a great commercial emporium, the center of Greek science and learning, and for three hundred years it continued to be the richest and largest city in the world.

As the members of the old Egyptian monarchy had proclaimed themselves sons of Ammon, Alexander, in order to regularize his position in the newly conquered province, made a visit to the temple of Zeus Ammon, traveling across the desert with a small company of troops. He was greeted by the priests of the temple as the divinely accredited ruler of Egypt, but the exact words of the response of the oracle were not communicated. They were kept as a mystery, but the divine honors claimed afterwards by Alexander were always connected with this mysterious attestation of his claim that his father was no earthly parent, but Zeus himself.