Most of the men in the room with Alexander had waded through rivers of blood in the course of winning their commands. The Indian campaign had been particularly harsh: Alexander had slaughtered civilians, even prisoners of war, hoping that this distant province could be terrorized into subjection. His generals followed such orders because they believed a greater good justified them. With the Persians subdued and tribes beyond the Caspian Sea and the Hindu Kush cowed into nonaggression, Alexander felt he was close to melding the whole known world into a single state. Religious and cultural freedom, economic development, and even (where possible) local autonomy would make the empire’s peoples willing sharers rather than grudging subjects. Alexander himself, his image carefully crafted to project tolerance, harmony, and progress, would be the banner under which the nations would unite.

All that was needed to bring this brave new world into being was the obliteration of those who threatened it, either by attack from without or by rebellion from within. The generals who helped conduct Alexander’s massacres were not butchers but loyal supporters of his driving vision. They had agreed to pursue his multiethnic world-state, certain they would one day share in rule over it. Indeed, Alexander had made clear how large a role they would have. In the royal pavilion he set up in Persis in his final year, a magnificent tent surrounded by thousands of elite troops in concentric rings, he stationed the Bodyguards on silver-footed couches directly around his own golden throne—the innermost orbit of the cosmos of which he formed the center.

Now these trusted generals were preparing to move against the Arabs, a people that had not directly threatened their empire. But after the army’s return to Babylon, when many unconquered peoples sent embassies to Alexander offering submission, the Arabs sent none. Their silence was worrisome because of their geographic position, astride the waterways connecting the empire’s Asian heartland to Africa and Europe. As foes, they could rob Alexander’s cities of trade revenue or limit the range of his warships. Under Macedonian control, conversely, their coasts offered harbors and anchorages for the ships that would sail, in Alexander’s plans, between the Mediterranean and the East.

The discussion that first night of Alexander’s illness focused on strategy and logistics. The army was more than adequate for the job ahead. The infantry phalanx, a massive block of warriors wielding eighteen-foot-long spears called sarissas, would form the anchor of the expeditionary force. The elite Companion cavalry, the army’s principal striking arm, would also be brought forward, and siege weaponry of all kinds—massive wheeled towers housing battering rams and drawbridges, catapults and artillery weapons newly designed by crack engineers—would be broken down into pieces and carried aboard ship. The fleet would also store provisions for the land army and materials for building the garrison towns that would dot the Persian Gulf coast, once the Arabs were subdued.

Alexander no doubt appointed the generals who would lead each unit. Perdiccas, as senior officer present, would have received command of the land army, since Alexander himself planned to travel with Nearchus’ fleet. Eumenes would assume his crucial new position at the head of a troop of Companion cavalry. No one could be sure how well a Greek would fill this role, never mind a Greek with no real combat experience, but Alexander seemed determined to find out.

When the meeting concluded, Alexander was carried out of the palace, placed aboard a ship, and taken up the Euphrates River, probably to the little Summer Palace in Babylon’s northern quadrant. Here there was what the Persians called a paradeiza( paradeisosto the Greeks, the root of “paradise”), a nature preserve and game park designed for the pleasure of Achaemenid kings, as well as cool breezes to temper the choking Mesopotamian heat. Alexander was seeking relief from the fever that had raged for a full day now, but also, in all likelihood, he wanted secrecy. After what had happened when he was near death in India, it was important that few people know how ill he was.

The senior staff who met with Alexander that first day convened again two days later, this time in the secluded quarters of the Summer Palace. The king’s condition was somewhat improved. His fever had come and gone intermittently, and he had at times been able to eat and converse. The Arabian campaign, now only two days away, was going ahead as planned.

During these days the generals must have talked about what they would face should Alexander’s condition worsen. They had reason to be anxious. The previous autumn a top officer, Hephaestion, then at the peak of health and strength, had succumbed in seven days to a fever much like Alexander’s. Moreover, both men had fallen ill after a bout of drinking, which raised the question of poison. At some point the generals must have acknowledged, to one another or to themselves, the possibility that Alexander was the victim of an assassination plot.

There were many who would be glad to see Alexander dead. The conquered Persians bore him little love, though on the whole they seemed a passive lot, content with the share of rule—a rather large share—Alexander had allotted them. Alexander’s Greek subjects, however, were feistier and less easily appeased. From their city-states in Europe they had mounted two rebellions already and were at that moment, as would soon be revealed, preparing to launch a third. Alexander had been taught by Greek tutors, including the philosopher Aristotle, and tried to show a commitment to Hellenic ideals, but his style was often that of an autocrat rather than a philosopher-king. Indeed, a Greek philosopher had stood against him when he proposed a plan that his courtiers should bow down to him in Persian style, and he had later found a pretext to have the man arrested or even (some sources say) executed. That man was Callisthenes, Alexander’s court historian, who happened to have been a relative and protégé of Aristotle’s. Was it possible that Aristotle, then living in Athens, had taken revenge by arranging the poisoning of his former student?

Then too there were the conservatives among the king’s Macedonian subjects, those opposed to his strange visions of shared empire and cultural fusion. Many such reactionaries had been purged, though one remained in power: old man Antipater, at this point past seventy, who had loyally guarded the Macedonian home front on Alexander’s behalf for twelve years, with help from his son Cassander, a man just Alexander’s age. But the king had resolved to unseat Antipater, either by retirement or a more extreme method. Alexander sent orders for him to surrender his post and report to Babylon, but for unknown reasons the senior general stayed put in Macedonia, sending his son in his stead. Cassander, who was known to dislike Alexander and to scorn the newly Asianized ways of the court, had arrived in Babylon only just before Alexander fell ill. Might he and his father, either out of hatred for what Alexander had become or out of fears for their own safety, have conspired to murder their king?

Many Greeks and Macedonians answered yes to these questions, in particular the latter. Rumors circulating at the time of Alexander’s death claimed that a lethal drink, collected by Aristotle from a spring that supposedly gave rise to the river Styx, had been brought to Babylon by Cassander at the behest of his father. The numbingly cold toxin, according to these rumors, had been transported inside a mule’s hoof, since it was said to eat through any other vessel, even solid iron, with its corrosive power. Then it had been slipped into Alexander’s cup by Cassander’s brother Iolaus, who, all too conveniently, was at that time the king’s wine pourer. The theory made sense from the standpoint of motive, means, and opportunity. It was so widely believed that Alexander’s mother, as will be seen, had Iolaus’ buried remains dug up and scattered as punishment for his presumed part in the plot.