The battle of Gaugamela in 331 b.c. decided the fate of the Persian empire. Darius was no longer the great king, for Alexander took the title as well as the dominions of his foe.
At Babylon, to which city Alexander now marched, the gates were thrown open to welcome him, the people coming out to meet the conqueror, led by their priests.
Alexander received them kindly, and bade the Babylonians not be afraid still to worship their own national god.
Here, in this great city, the king dreamed that he would set up his throne. Babylon should be the capital of his new empire.
Not far from Babylon was the city of Susa, where the Persian kings usually spent the winter months. Susa also surrendered to the great king without a blow being struck.
There were many treasures and much gold in both Babylon and Susa; perhaps the most wonderful treasure was a piece of purple cloth, which was worth an enormous sum of money. Although it had been laid aside for one hundred and ninety years, yet its marvellous colour was as perfect as it had ever been.
The spoils for which the Greeks cared most were some that had been carried away by Xerxes. Among those that they found at Susa were statues of Harmodius and Aristogeiton. By the order of Alexander, they were now sent back to Athens.
But even greater treasures than any the king had yet found were stored in palaces hidden among the highlands of Persia. To these palaces Alexander resolved to march, although the way led through narrow mountain passes which were guarded by a Persian army.
By attacking the enemy both in the front and in the rear, Alexander caught the Persians in a trap. They were speedily cut to pieces or fell down the dangerous mountain tracks in a vain effort to escape.
Then unhindered by any foe, the king marched on to one of the great cities of the Persian kings, which the Greeks called Persepolis, or "the richest of all the cities under the sun."
So great were the treasures stored in the palace of Persepolis, that ten thousand pairs of mules and five thousand camels were needed to carry them away.
For four months Alexander lingered in the city. His soldiers were proud indeed of their king when for the first time they saw him sitting under a canopy of gold on the throne of the Persian monarchs.
A Corinthian, who was a great friend of Alexander's, exclaimed at the sight, "How unfortunate are those Greeks who have died without beholding Alexander seated on the throne of Darius!"
Before he left Persepolis to go in search of Darius, Alexander gave a great feast.
It was then that the king, urged by the excited revellers, allowed the palace to be burned.
With a wreath of flowers on his head and a lighted torch in his hand, the king, followed by his guests, surrounded the palace, and set light to it. The soldiers also seized torches and amid shouts and merriment they, too, helped to destroy the palace of the Persian kings.
The Macedonians thought that the burning of the palace was a sign that Alexander did not mean to dwell among the barbarians, and they rejoiced. For they were growing weary of marching into unknown countries, and they were beginning to think wistfully of their homeland.
Alexander was soon sorry for the wild impulse which had seized him, and he gave orders to put out the fire as speedily as might be.
The officers in Alexander's army had become rich with the spoils of conquered cities, and the king found that they were growing as fond of ease and luxury as the Persians. Their tables were loaded with delicacies, servants attended to their slightest wish. One officer even had his shoes made with silver nails.
Such indulgence annoyed the king and he reproved his officers, telling them that toil was more honourable than pleasure.
"How is it possible," he said, "if you cannot attend to your own body, that you look well after your horse, or keep your armour bright and in good order? You should surely avoid the weaknesses of those you have conquered."
To set his army an example, the king now began to hunt more than was his custom and with less care for his own safety. When the soldiers were sent against an enemy, Alexander himself went with them, and endured the same hardships and dangers as his men.