Part 1 - The Battle of Salamis
Having been quiet since 315 Polyperchon, seeking to improve his position, championed Heracles, the illegitimate son of Alexander the Great, as the heir to the Macedonian throne. However, he then secretly agreed to Cassander’s terms, had Heracles killed, and allied with Cassander. Meanwhile, Ptolemaeus, nephew of Antigonus, defected to Cassander, weakening the Antigonid position in Greece. in 307 Demetrius, son of Antigonus, successfully captured Athens and Megara, earning honours from the Athenians. He then led a campaign against Ptolemy in Cyprus, defeating Menelaus at Salamis and constructing a massive siege engine. However, Ptolemy arrived with reinforcements, forcing Demetrius to engage in a decisive naval battle. Demetrius defeated Ptolemy in a large naval battle near Salamis, Cyprus. Demetrius’ superior tactics and stronger forces led to a decisive victory, capturing or sinking most of Ptolemy’s fleet. This victory significantly shifted the balance of power among the Diadochi, solidifying Antigonid dominance in the region. Demetrius’s victory at Salamis in 306 BCE solidified Antigonid power in Asia Minor and the Levant. This led Antigonus to proclaim himself king, a title Demetrius also adopted, prompting other Diadochi to follow suit.
Part 2 - Antigenic invasion of Egypt
Following Demetrius’ victory at Salamis, Antigonus planned an invasion of Egypt to eliminate Ptolemy. Despite assembling a massive army and fleet, Antigonus faced challenges including desertions, storms, and strong Ptolemaic defences. Demetrius’ attempts to land behind Ptolemy’s forces were thwarted, leading to a retreat and further losses due to the storm. Antigonus Monophthalmos’s invasion of Egypt failed due to strategic miscalculations, logistical challenges, and Ptolemy’s effective defences. Antigonus’s decision to invade during the Nile’s flood season and his failure to secure a successful naval landing hampered the campaign. Additionally, Ptolemy’s use of Egypt’s natural fortifications and his ability to maintain support among his troops and other Macedonian leaders proved formidable obstacles.
Part 3 - The Siege of Rhodes
In 305-304 BCE, Antigonus and Demetrius, recovering from a failed invasion of Egypt, laid siege to Rhodes. The Rhodians, who had refused to aid the Antigonids against Ptolemy, were seen as a threat due to their control of grain trade between Egypt and Greece. Despite initial attempts at diplomacy, Demetrius besieged the city with a massive fleet and army, forcing the Rhodians to prepare for war.
Demetrius attacked Rhodes, focusing on the harbour with siege engines and a fleet of light ships. Despite initial successes, including capturing part of the mole, the Rhodians fiercely resisted, damaging his equipment and forcing a retreat. A storm destroyed Demetrius’ new siege engine, and a subsequent Rhodian attack captured his fortified position on the mole.
In 304 BCE, Demetrius Poliorcetes, unable to capture Rhodes by sea, switched to a land assault. He constructed the Helepolis, a massive siege tower, and other siege engines, while the Rhodians fortified their defences and launched naval raids against Demetrius’s fleet. Despite Demetrius’s efforts, including tunnelling and a full-scale assault, the Rhodians held out, receiving aid from Ptolemy and other allies. Demetrius, unable to capture Rhodes after a year-long siege, was forced by external events to abandon the siege. The siege’s failure weakened the Antigonids, allowing other Diadochi to assert their power and led to the downfall of the Antigonid house.
Part 4 The Battle of Ipsus
The Battle of Ipsus in 301 BCE was a decisive conflict among the Diadochi—the successors of Alexander the Great. Antigonus Monophthalmus, whose ambition and military prowess made him the Diadoch closest to reuniting Alexander’s vast, fractured empire, made one last attempt to reunite it. Antigonus, was both an antagonist and protagonist in the struggle for supremacy, frequently inciting responses and alliances among his rivals by his bold actions and strategic gambits.
By the time of Ipsus, Antigonus was elderly, overweight, and physically diminished, no longer possessing the same vigour that had driven his earlier campaigns, such as his failed attempts to retake Babylon in 311/10 BCE or his unsuccessful campaign against Egypt in 306 BCE. Despite these limitations, Antigonus remained a formidable figure until his death at Ipsus, which effectively ended any realistic hope of restoring Alexander’s unified empire. His son, Demetrius, though competent in his own right, lacked his father’s extraordinary capabilities.
Ipsus, or a battle like it was inevitable, but the catastrophe accelerated the decline of the Antigonids.
The aftermath of the battle saw the permanent division of Alexander’s empire into multiple Hellenistic kingdoms, with the Diadochi continuing to contest borders and authority, but never again coming close to full reunification.
Sources:
Ancient Sources:
Diodorus Library of History 20-21
Plutarch Demetrius
Plutarch Pyrrhus
Modern Sources:
Anson, Edward Alexanders Heirs
Ellis, Walter M. Ptolemy of Egypt
Green, Peter Alexander to Actium
Pietrykowski, Joseph Great Battles of the Hellenistic World
Romm, James Demetrius: Sacker of Cities
Tarn, W. W. Hellenistic Military and Naval Developments
Waterfield, Robin Dividing the Spoils