Discovering that many of his satraps and military governors had misbehaved in his absence, Alexander executed several of them as examples on his way to Susa. As a gesture of thanks, he paid off the debts of his soldiers, and announced that he would send over-aged and disabled veterans back to Macedon, led by Craterus. His troops misunderstood his intention and mutinied at the town of Opis. They refused to be sent away and criticized his adoption of Persian customs and dress and the introduction of Persian officers and soldiers into Macedonian units.

After three days, unable to persuade his men to back down, Alexander gave Persians command posts in the army and conferred Macedonian military titles upon Persian units. The Macedonians quickly begged forgiveness, which Alexander accepted, and held a great banquet for several thousand of his men at which he and they ate together. In an attempt to craft a lasting harmony between his Macedonian and Persian subjects, Alexander held a mass marriage of his senior officers to Persian and other noblewomen at Susa, but few of those marriages seem to have lasted much beyond a year. Meanwhile, upon his return, Alexander learned that guards of the tomb of Cyrus the Great had desecrated it, and swiftly executed them.

After Alexander traveled to Ecbatana to retrieve the bulk of the Persian treasure, his closest friend and possible lover, Hephaestion, died of illness or poisoning. Hephaestion’s death devastated Alexander, and he ordered the preparation of an expensive funeral pyre in Babylon, as well as a decree for public mourning. Back in Babylon, Alexander planned a series of new campaigns, beginning with an invasion of Arabia, but he would not have a chance to realize them, as he died shortly thereafter.