The phenomenon of Alexander's 'successors' — the Diadochi — and the wars they fought to carve up his empire from 323 to 281 BC represent forty years of almost continuous conflict that produced the Hellenistic world order but also reveal how fragile Alexander's personal empire had been.

Alexander left no designated heir (his posthumous son Alexander IV was murdered as a child; his half-brother Philip III Arrhidaeus was reportedly mentally incapacitated). The immediate response was competing claims from the major Macedonian commanders, who had divided the empire into satrapies at the settlement of Triparadisus in 320 BC.

The wars of the successors involved military commanders of extraordinary ability — Antigonus the One-Eyed, Seleucus, Ptolemy, Lysimachus, Cassander — fighting shifting coalitions over two generations. The decisive battle was Ipsus in 301 BC, where Antigonus died and his claim to a reunified empire died with him. The subsequent settlement divided the empire into the main successor kingdoms that would characterize the Hellenistic world.

The wars produced innovations in Hellenistic warfare: the increased use of war elephants (acquired from Indian sources after Alexander's campaigns), the development of larger warships, and the deployment of siege artillery. The famous siege of Rhodes by Demetrius Poliorcetes in 305–304 BC, which Rhodes successfully resisted, gave Demetrius his epithet ('the Besieger') and generated the surplus artillery and materials that Rhodes sold to fund the Colossus, one of the Seven Wonders.