Who was Aeacus in Greek Mythology

Aeacus was the son of Zeus and the nymph Aegina, daughter of the river Asopus, inhabitant and first king of the island, which was first called Oinonis and which at some point was left without inhabitants.
This happened when Hera learned that Zeus had another son and out of her anger sent a snake to a river in Aegina, where she laid thousands of eggs and snakes overran the island.

And yet, a warm air that lasted for months, they knew the island. Under these harsh conditions the inhabitants of the island died and Aeacus was left alone. To his pleas and lamentations father Zeus answered with lightning and causing an oak tree to grow, the sacred tree of the heavenly father.

When Aeacus saw a great number of ants living in the hollow of the tree climbing up its trunk holding pimples, he begged his father to give him as many subjects as there were ants. And Zeus transformed the insects into men, and Aiacus named the new inhabitants of Aegina Myrmidons. Later, we find them campaigning in Troy led by Achilles, a descendant of Aiacus. Of course, hidden in this myth, according to Strabo, is the fact that the inhabitants of Aegina used the method of ants to clear the land and make it arable.

Aeakos married Endeida from Megara, daughter of Sciron, and had two sons, Peleus, the later father of the heroic Achilles, and Telamon, father of the equally heroic Aedas, who, according to legend, raised the dead Achilles and transports to the Achaean camp, so that the Trojans do not possess and dog his body.

But this was not the only marriage that Aeacus entered into, nor did he stay only with these two boys. He fell in love with a Nereid, Psamathi, who, like her sister Thetis, had the ability to transform. To avoid Aiacus, she assumed various forms, until she became a seal; however, Aiacus managed to sleep with her. From their union a child was born who was justifiably named Fokos.

When the child grew up, he left his father’s homeland, Salamis, for Central Greece, where he conquered the country that he named Phocis. There he married and had children. Later he went to Aegina, where his distinctions in athletic contests aroused the jealousy of his half-brothers, who cast lots to determine by fate who would kill him who might be their father’s special son.

The lot fell to Telamon, who, as he was exercising, threw his discus in such a way as to knock Phocus on the head; together the two brothers, Telamon and Peleus, buried the body in a forest. When Aeacus discovered the murder, he exiled his children from Aegina; Telamonas went to Salamis and Peleus to Phthia in Thessaly. Meanwhile, other sources attribute the murder to Peleus and the motivation to the brothers’ willingness to satisfy their mother:

When Telamonas and Peleus challenged Phocus to a pentathlon and it was Peleus’ turn to throw the stone, which they used instead of a disk, he deliberately hit Phocus. They did it to please their mother, because they had been born from the daughter of Skiron, while Phokos was not from her, but from a sister of Thetis, if what the Greeks say is correct.

There is also the version that the two together, Telamonas and Peleus, killed the half-brother or that the death of Phokos was accidental, but they could not convince that there was no envy and deceit. Aeacus did not allow Telamonas to return from exile to his birthplace:

When Phokos was killed by the discus, the children of Enidida boarded a boat and left. Later Telamonas sent a herald denying that he had planned the death of Phokos, but Aeacus did not allow him to land on the island and told him, if he wanted, to excuse himself from the ship or from being buried in the sea. So he sailed to the port called Krypto and during the night he made an embankment, which was completed and exists to this day. But because he was found guilty of the murder of Phokos, he fled a second time to Salamis. This time the escape was final.

When Zeus ordered Poseidon and Apollo, for the conspiracy they had hatched against him, to serve in mortal form Laomedon, king of Troy, as a punishment, he asked them to wall Troy—which is also called Pergamos.

And they did it with Aeacus by their side. So the walls were not built by gods alone, which would make Troy unnumbered, even by gods. Indeed, when the building was finished, dragons mounted the walls and were only able to scale them in the section built by Aiacus. And Apollo prophesied then that Troy would be conquered more than once and that among the conquerors there would also be Aiakids, just as it happened with Telamon initially at the side of Herakles, Neoptolemus later, son of Achilles and great-grandson of Aiacus.

According to Pliny, Aeacus discovered silver and minted the first coin. A wise, just and pious man, he ruled Aegina with these virtues. And because he had put justice above his sons and banished them for their crime—the murder of their half-brother Phocus—he was esteemed by all the Greeks. Once upon a time when there was a great drought throughout Greece as a punishment for Pelops having killed, dismembered and scattered the members of Stymphalus, the king of Arcadia, the oracle of Delphi foretold that only Aeacus could save them.

According to Isocrates, it was the prefects of the cities who begged him, because a drought had fallen and thinking that because of his kinship and piety, if he found himself before the gods, the present evils would be absolved. Indeed, Aeacus prayed to the father of all and his own father, Zeus, who heard the beloved son’s prayer and sent torrential rain. And from then on, a priest was established in Aegina as a community of the Greeks, for whom he performed the blessing (ibid. 15.2).

Zeus had a special liking for this pious and righteous son and wanted to make him ageless, but this was beyond his jurisdiction. But when Aeacus died and went down to the Underworld, Hades and Persephone welcomed him with great honors and appointed him the key and judge of Hades together with two other sons of Zeus, Rhadamanthus and Minos.
And the former judged the Asians dead, Aiacus the Europeans and Minos those about whom his brothers had doubts. But, of course, the addition of the third judge is Platonic, Homer ignores the fact. [For an Aristophanic rendering of the Aiacus see food binding]

The Aeginites especially honored his memory, they even organized annual celebrations, the Aiakeia. In the center of the city there was the Aiakia sanctuary, built with white marble, where according to a tradition his tomb was located surrounded by olive trees. Apart from Aegina, his memory was commemorated in various parts of Greece. In Athens, in fact, a number of important families considered themselves descended from Aeacus . Many glorious Athenians such as Miltiades, Cimon, Thucydides and Alcibiades belonged to the Aeakids.