With the exception of the battle of Salamis (306 BC.), the naval conflicts during the wars of the Diadochi are often overlooked. In an attempt to correct this, here is an overview of the main naval events of the early years of the conflict from 323 to 318 BC. This period saw a number of major naval engagements and these played a decisive role in shaping the course of the wars.
The first major naval clashes took place during the Lamian War. At the outset of this conflict Athens raised a fleet of about 240 ships, although only about 40 were larger than Triremes. This vast investment in a navy tells us how important the Athenians viewed control of the sea. They understood that if they could prevent reinforcements being brought over from Asia, that they stood a real chance of defeating Antipater. As it was, they could not and the successive reverses suffered by the Athenians at sea condemned them to defeat.
Because of the deficiencies of our sources we cannot say for certain if the Lamian War saw two or three naval battles. The following is what I believe was the most likely course of events. In the Spring of 322, the Macedonian admiral Cleitus (the White) engaged the Athenians, commanded by Euetion, off Abydos and won a resounding victory. This handed the Macedonians control of the sea and meant they could bring Antipater reinforcements unhindered.
Cleitus might have fought another Athenian squadron in the Malian Gulf not long afterwards. If so, it would suggest that the force he defeated at Abydos was not the entire Athenian fleet of 240 (yet it is accepted that the fleet at Abydos consisted of the bulk of Athenian naval power). Athens immediately outfitted a new fleet, an incredible effort, and prepared for another confrontation. They probably managed to re-equip and build a force of around 170 ships. In the summer of 322, probably July, Cleitus met Euetion again in a decisive battle off the Amorgos Islands. The Athenian fleet was destroyed and signaled the end of Athenian naval power. It also marked the end of Greek hopes and handed the Macedonians victory in the war. The Greek allies did hazard another pitched battle on land, at Crannon, in September 322. However the situation at sea meant that nothing less than a knock-out victory would save them. They fought the Macedonians to a standstill, but it was not enough.
What undid the Greeks was their reliance on the Black Sea trade routes for food to feed their people. Cleitus' victories allowed the Macedonians to blockade Greece and slowly begin to strangle the Greek war effort. For this reason the Amorgos Islands spelt the effective end for the Athenians. The question does have to be asked, why was Euetion allowed a second command after his first defeat off Abydos? This is not to suggest another admiral would have done better, but considering how in the past Athenian admirals were often blamed for the loss of citizen lives, even when they won, it is surprising that Euetion was not replaced. Perhaps the Athenians realised that in Cleitus they faced a skilled commander and that only an experienced man stood any chance?
We know little enough about the ships used in this period. Diodorus tells us the Athenians built 200 triremes and 40 quadriremes (Justin says only 200 ships in total). No figures are given for the Macedonian fleet. Cleitus, one of Alexander's men, probably commanded a mixed force of Macedonian, Cypriot and Phoenician ships. We know that within about ten years of this period Antigonus had begun commissioning much larger ships to be built in Syria and Phoenicia, so it is not unreasonable to suppose that the Macedonian fleet not only outnumbered the Athenian fleet, but that it had significantly more big ships. Athens had a proud record at sea, but surely nothing demonstrated more clearly that the age of the city state was done than the mismatch in naval power and technology now displayed.
Cleitus, and his fleet, seem to have stayed attached to Antipater at this point and sided with him against Perdiccas as the next phase of the conflict began. However his was not the only fleet and so when invading Egypt, Perdiccas took a fleet of unknown size with him, commanded by his brother-in-law, Attalus. After Perdiccas' murder, Attalus fled with his fleet to Tyre where he collected men and money. Joining with Alcetas, Perdiccas' brother, they launched an attack on Rhodes (probably in 320). This was defeated by the Rhodian admiral, Demaratus. W. W. Tarn speculates that Attalus may also have attacked Cyprus, but that this invasion was defeated by Cleitus and the Athenian admiral, Thymochares (notice the Athenian navy had now been reduced to a support role). If so this would confirm that Cleitus was allied with Antipater, or at least that he recognised him as the legitimate Regent of the Empire.
This is an important distinction. Because after Antipater's death Cleitus sided with Polyperchon against Cassander, Antipater's son. Cleitus' control of the sea was vital to Polyperchon's hopes of defeating Cassander, as the latter was depending upon Antigonus sending him help from Asia. If Cleitus could prevent Antigonus crossing to Europe, Cassander's war effort would be severely hit.
Cleitus engaged Nicanor, who was allied to Cassander and Antigonus, in a naval battle off Byzantium in the summer of 318. If we accept all of the above this would be Cleitus fifth naval engagement and, not surprisingly, his knowledge of naval combat proved too much for Nicanor, winning him the battle. From 130 ships, Cleitus succeeded in capturing or sinking 60. This should have been decisive, but Antigonus arrived and, with the connivance of the Byzantines, launched a surprise attack by land and sea the following day. Caught in their camp, just as the Athenians had been at Aegospotami almost a century ago, Cleitus' forces were swiftly captured or destroyed. Cleitus himself escaped, only to fall into the hands of Lysimachus who had him killed.
This battle off Byzantium effectively brought the first period of naval combat in the wars of the Diadochi to an end. In the succeeding years the main trend, in a naval sense, was Ptolemy's growing power. Finally to counter this, Antigonus ordered a massive shipbuilding program which would eventually result in the decisive battle of Salamis (306) handing Demetrius control of the Eastern Mediterranean for a generation.