The battle of Amorgos saw the final defeat of Athenian naval power. After the death of Alexander the Great, the Athenians had seen a chance to win their independence, and had raised an army and a fleet (Lamian War). That fleet, under the command of a commander called Euetion, had been sent to the Hellespont in an attempt to prevent reinforcements reaching the Macedonians in Greece.
In the first few years after the death of Alexander, his generals kept alive the illusion of a united empire. In 322 Alexander’s military machine was still intact, and part of it now sprang into action. One of his generals, Craterus, sent one of his commanders, Cleitus, to take command of the Macedonian fleet. Cleitus then won a victory over the Greek fleet at Abydos, driving them away from the Hellespont, but not destroying the fleet. This victory allowed Macedonian reinforcements to reach Greece, but the existence of the Athenian fleet prevented Craterus from shipping a larger army across the Aegean.
By the summer of 322 B.C. the Athenian fleet had been reinforced, and now contained 200 ships. The two fleets came together again at Amorgos, sixty miles south west of Samos. Once again Cleitus was victorious, this time inflicting a crushing defeat. Athens’s last great war fleet had been destroyed.
With control of the sea lost, the Greek cause was doomed. The Macedonians were able to ship reinforcements to Greece, led by Craterus. The Greek army was defeated at Crannon, and faced by the prospect of a siege Athens surrendered.