Early in 288, while Ptolemy’s admiral sailed for southern Greece with the intention of stirring the Greek cities to rebellion, Lysimachus and Pyrrhus attacked Macedon from, respectively, the east and the west. Pyrrhus employed the old Successor tactic of claiming that Alexander the Great had appeared to him in a dream and promised his aid. Demetrius left Gonatas to take care of the Ptolemaic threat in southern Greece and, unaware of Pyrrhus’s treachery, concentrated his forces in the east to face Lysimachus. He learned just how unpopular he was when his Macedonian troops deserted, first to Lysimachus and then to Pyrrhus, when Demetrius heard of his invasion and turned to confront him.

It was the most effective coup imaginable. Demetrius was thrown out of his kingdom by the army, or its senior officers, after six years on the throne. But Macedon was left to endure, for a second time, the uncertainty of a dual kingship. Pyrrhus justified his rulership by citing his kinship to Alexander the Great (they were second cousins), and took western Macedon (and then Thessaly a few years later); Lysimachus gained the eastern kingdom—a significant gain for him, given the wealth of Macedon’s natural resources there. For instance, with what he already had in Asia Minor, he now monopolized the most accessible sources of gold.

Demetrius adopted a lowly disguise and fled to Cassandreia. Elderly Phila saw the end and took poison. Her marriage to Demetrius had been long and apparently stable, despite his tempestuous career. She was clearly a formidable woman; even when she was young, her father had consulted her on official business, and she came to have her own court, Companions, and bodyguard, as well as cults in Athens and elsewhere. She was an early prototype of the powerful and independent queens of the later Hellenistic period.

From Cassandreia, Demetrius joined Gonatas in southern Greece. He was reduced once again to his fleet, his Companion Cavalry, and however many mercenaries he could afford to keep. Astonishingly, and with the help of his capacious treasury, he was able to keep himself relatively secure in Corinth, and over the next two years even built up his land army again. Athens seized the moment, however, and rose up against him in the spring of 286. Those of the Antigonid garrison who refused inducements to defect were defeated in battle. Ptolemy allowed Callias of Sphettus, an Athenian in his service, to detach a thousand elite troops from the Cyclades to protect the harvest against attacks by troops from Demetrius’s other garrisons.

Demetrius arrived, with a larger army than expected, and the besieged Athenians sent for help from Pyrrhus. But then a Ptolemaic fleet appeared off Piraeus, so that Demetrius, who was in any case still insanely anxious to take the war to Asia, could see that he would be tied up in Athens for ages. He came to terms with Ptolemy and Pyrrhus, who appear to have been just as anxious not to fight. Athens would remain ungarrisoned, but Demetrius was allowed to keep his other garrisons in Piraeus and in fortresses nearby. As far as Athens was concerned, this made it a truce, not a treaty. When Pyrrhus arrived, he is said to have recommended that the Athenians never admit a king within their walls again. ¹⁶Perhaps it was a warning against his own ambitions. Demetrius left his remaining European possessions in the hands of Gonatas and set out immediately for Asia Minor. Disturbingly for Lysimachus, Ptolemy’s Aegean fleet made no attempt to impede the invasion. Miletus defected to Demetrius, presumably by prearrangement, and gave him a first base. At Miletus, he was met by Eurydice, Ptolemy’s ex-wife, and sister of Phila. She brought her daughter Ptolemais, to whom Demetrius had been betrothed in 298, and they now married. But the marriage was no kind of rapprochement with Ptolemy; things had changed in the twelve years since the couple were first betrothed. Eurydice was in exile, estranged from Ptolemy, and she had other designs. She saw alliance with Demetrius as a way to give her son a chance at power, since his prospects in Egypt were not good: Ptolemy had long favored his other wife Berenice and her offspring. The very next year, in fact, Ptolemy abdicated in favor of his son by Berenice, who became Ptolemy II. Eurydice’s son was called Ptolemy Ceraunus, the Thunderbolt—named not “for his unpredictable and sinister character,” as hostile propaganda claimed, ¹⁷but for the power he wielded.

The campaigning season of 285 started well for Demetrius. He regained a few coastal towns, including Ephesus (presumably by treachery, if the Lysimachan fortifications briefly described earlier were already in place), and subsequently Lysimachus’s governors in Lydia and Caria surrendered their territories wholesale. There is no way to explain these rapid successes except by assuming that he was welcomed. Before Ipsus, Asia Minor had been under Antigonid rule for a long time, and had prospered; it seems that enough of the inhabitants wanted to turn back the clock.

Meanwhile, Pyrrhus invaded Thessaly, which drew Gonatas’s attention northward, and Athens made an attempt to dislodge the Antigonid garrison in the Piraeus. The year before, they had persuaded one of the garrison commanders in Athens to defect with some of his men. They tried the same tactic again in Piraeus, but this time it ended in disaster. The man only pretended to go along with their plan. He opened the fortress gates to the approaching Athenian soldiers by night—but only to trap them inside and cut them down.

In Asia Minor, despite his first successes, Demetrius was losing the initiative. Lysimachus’s son Agathocles was demonstrating that he had inherited his father’s skills as a general. He drew Demetrius ever farther inland—the same strategy the Turks used in 1920–21 against the Greek invasion—while cutting him off from the coast by retaking the territories now in his rear that he had just taken himself, including Sardis and Miletus. Demetrius’s fleet at Miletus either fled to safe refuges farther down the coast or surrendered. With their supply lines cut and their hopes rapidly fading, Demetrius’s mercenaries began to desert him. Their commander claimed to be unconcerned, on the grounds that he could always find more men to recruit in Media, which he planned to reach via Armenia. By now he seems decidedly unbalanced; not content with being defeated by Agathocles, he was threatening Seleucus too, but with diminishing forces.

Demetrius was perhaps intending to encourage the often restless eastern satrapies to rise up and, with his help, overthrow Seleucus. But this was an unlikely scenario, not least because Seleucus had elevated his son Antiochus—”the only anchor for our storm-tossed house” ¹⁸—to joint kingship in 294 or 293 and sent him east to quell any storm. In the longer term, it made sense to have a coruler for such a vast kingdom, and for the east, one who was half-Iranian and had been brought up in Babylon. At the same time, Seleucus gave Antiochus his wife Stratonice. Despite fanciful stories of illicit passion, ¹⁹what was uppermost in his mind was probably to try to ensure stability within his household, since otherwise any son Stratonice might have borne him would have been a rival to Antiochus. It was also a way of keeping Demetrius within the family, so to speak, while simultaneously announcing a certain cooling of their relationship.

So no uprising took place in the eastern satrapies to aid Demetrius’s plans. Instead of heading for Armenia, he turned south, with disease and desertion decimating his numbers. Agathocles let him cross the Taurus Mountains into Cilicia, and strengthened the fortresses on the passes against his return. He was Seleucus’s problem now. Seleucus tolerated Demetrius’s presence for a while, but had to take steps in the spring of 284 to contain him in the mountains. Demetrius reacted with some vigorous guerrilla warfare, and even threatened to enter Syria until he was laid low once again by illness.