The death of the mighty Heracles (Ἡρακλἣς) brought a problem to his many sons.

Eurystheus (Εὐρυσθεύς), cousin of Heracles, was the ruler of two powerful kingdoms Tiryns and Mycenae. Eurystheus' right to rule in Tiryns was only through the intervention of the goddess Hera, so that he was born days before Heracles. Hera had cheated Heracles of his inheritance, the kingdoms of Mycenae and Tiryns (see Birth of Heracles). While Heracles lived, Eurystheus lived in constant fear that his cousin would one-day depose him. During Heracles' campaign in Elis, Eurystheus banished his cousin from his kingdom because of his paranoia.

Eurystheus wanted to ensure that none of his nephews would survive to rule in his kingdom, so the wicked king persecute the sons of Heracles, known as the Heraclids (Ἡρακλειδαί). Eurystheus gathered a large army in Tiryns. Eurystheus sent messages throughout Greece, warning that any rulers who dared to offer hospitality and shelter to the Heraclids in their kingdoms would face the invasion of his army.

Heracles' last home was in Trachis, a city in southern Thessaly. Trachis was the home of King Ceyx, but he could not hope to resist against Eurystheus' larger army, nor could he protect the sons of his friend. So he told the Heraclids that they must find a stronger ally than him. Iolaus (Ἰόλαος) led the Heraclids to Marathon, in Attica.

Iolaus (Ἰόλαος), son of Iphicles, hence he was a nephew to both Heracles and Eurystheus. He was a faithful companion of Heracles, often serving as squire and charioteer to Heracles. Though, Iolaus was strong and brave in his youth, he was now an old man, so he could not hope to protect his younger cousins. Iolaus helped Heracles against the monster Hydra, and faced Cyncus and Ares with Heracles. Iolaus had also defeated Glaucus in a chariot race.

In Athens, Iolaus and the Heraclids were suppliants, asking for aids from Demophon, son of the Athenian hero, Theseus. Heracles and Theseus were cousins and friends, and for the sake of old tie, Demophon send his own force to Marathon.

Eurystheus sent an envoy to Demophon, demanding the surrender of children of Heracles, which the Athenian ruler refused. A battle was about to take place in Marathon. Iolaus and the Heraclids heard from the oracle that only a sacrifice of one of the Heraclids would ensure that the Athenians would win in battle. Macaria was the only daughter of Heracles, and she volunteered to be sacrificed.

In the shrine at Marathon, old Iolaus took the armour and weapon from the altar. Iolaus prayed to the gods to give him his strength for one day, so that he could fight like he did when he was a companion of Heracles. His prayer were answered, and Hebe, Heracles' wife in Olympus, restored Iolaus' youth and strength for a single day.

The tide in battle turned against the Eurystheus' army, and all four of the king's sons were killed. Iolaus pursued Eurystheus to Sceironian Rock. In some versions, either Iolaus or Hyllus (Ὕλλος), the eldest son of Heracles and Deïaneira (Δηιάνειρα), killed him. But in Euripides' tragedy, Iolaus captured and brought the defeated king to his grandmother, Alcmene, mother of Heracles and Iphicles, Iolaus' own father.

The Athenians were reluctant to kill a prisoner of war, but Alcmene was adamant that Eurystheus deserved death. Alcmene took revenge upon Eurystheus for persecuting her grandchildren, by gouging out the king's eyes, using weaving pins to drive it into his brain. According to Pindar, Iolaus cut off Eurystheus head with his sharp sword.

The Athenians gave honorable burial to Eurystheus, because the king had foretold before his death that if they kept his body in Attica's soil, it would protect them from the Heraclids in the future.

When Iolaus died, according to Pindar, he was buried beside his grandfather, Amphitryon, near the Sparti gate at Thebes.

• Hyllus
• Exile and Return of the Heraclids

The sons of Heracles then set out to invade the Peloponnese, under the leadership of Hyllus (Ὕλλος), son of Heracles and Deïaneira. Though, they had conquered many lands, after one year they were driven out by the plague and famine.

Hyllus went to consult the oracle in Delphi, and he was told that they had invaded the Peloponnese at the wrong time of the year. They were told that they should wait for the third harvest. Hyllus assumed that the oracle meant that they should wait for three years.

Three years later, Hyllus returned to the Peloponnese with an army, and were confronted by Atreus and his allies on the Isthmus of Corinth.

Tlepolemus, whose mother was Astyoche, was beating his servant, when he accidentally killed his uncle, Licymnius. His half-brothers forced Tlepolemus to go into exile. Tlepolemus and his followers sailed to Rhodes, where he founded the cities of Cameirus, Ialysus and Lindus. Tlepolemus would later take nine ships to Troy, where the Lycian captain, Sarpedon, he killed him. So Tlepolemus didn't take part in this battle.

Hyllus challenged the other side that one champion should fight him, agreeing to withdraw for fifty years, if he were to lose. Echemus (Ἔχεμος), who was king of Arcadia, accepted the challenge and killed Hyllus. Hyllus was buried in Megara.

With Hyllus' death, the Heraclids withdrew from the Peloponnese. A truce between the two sides, where the Heraclids can't return to the Peloponnese for fifty years.

Exile and Return of the Heraclids

The Heraclids invaded Peloponnese again, after the fifty-year truce ended, under the leadership of Aristomachus (Ἀριςτόμαχος), a grandson of Hyllus. Tisamenus, son of Orestes, confronted the Heraclids, with army from Argos and Sparta. Aristomachus was killed in one of the raids. They returned north, and consulted the oracle again. The oracle gave them the same answer it did the last time.

The Heraclids were then led by Aristomachus' three sons: Temenus (Τήμενος), Aristodemus (Ἀριςτόδημος) and Cresphontes. Their army was gathered at Naupactus in Locris, where they also constructed ships. Aristodemus was killed by a thunderbolt, so his sons Procles and Eurythenes took command of their father's warriors.

Another disaster struck the Heraclids, when Hippotes, another Heraclid, killed a diviner, whom they thought was a sorcerer, sent to cause mischief. The diviner's death caused destruction of their ships and famine across the land. The Heraclids had to disband because of the new disaster.

Temenus consulted the oracle again, and was told that they were being punished for killing the diviner. Following the oracle's instructions, they banished Hippotes for ten years because of the murder, and began a search for the Three-Eyed One. They discovered the Three-Eyed One, when they encountered Oxylus (Ὄξυλος), but no, he doesn't have three eyes. Oxylus was riding a one-eyed horse.

Oxylus, son of Andraimon, comes from Elis, which he fled because he was banished for murder or accidental killing. So Oxylus acted as the guide to the Heraclids, in return for the fertile land of Elis.

In the war that followed, the Heraclids were finally given victories in their battles. Tisamenus, the son of Orestes, and king of both Argos and Sparta, was killed. On the Heraclids' side, the two sons of Aegimius, Pamphylus and Dymas, had also died in the fighting.

They rewarded Oxylus with the kingdom of Elis, while they divided the rest of the Peloponnese among themselves. They drew lots. Temenus received Argos, Procles and Eurysthenes had to share the kingdom of Sparta, and Cresphontes received Messenia.

It was said that Cresphontes had won Messenia through trickery, so that his nephews received Sparta, and had to share powers.

In Argos, the situation would turn sour for Temenus.

While Temenus was ruling Argos, he favoured his daughter Hyrnetho and her husband Deiphontes more than he did with his own sons - Agelaus, Eurypylus and Callias. Deiphontes was the son of Antimachus and also a Heraclid. Temenus had appointed Deiphontes as his chief adviser.

Temeneus' sons arranged for his murder. But their plots were in vain, because Hyrnetho and Deiphontes succeeded Temenus, with the full support of the army.

The Greek geographer, Pausanias, gives more detail of the event between Deiphontes and Temenus' sons, in relation to the grove called Hyrnethion.

Here, Pausanias listed Temenus' sons as Ceisus (Keisos), Cerynes (Kerynes), Phalces and Agraius (Agraios). When they murdered their father, it was Ceisus who seized the throne, because he was the eldest. Hyrnetho and Deiphontes fled to King Pityreus in Epidaurus, a kingdom west of Argos.

Ceisus fearing his brother-in-law, send Cerynes and Phalces to bring back their sister, promising to find a better husband for Hyrnetho. Agraius, the youngest son opposed to this plot.

When Hyrnetho, who was pregnant with their fifth child, refused to leave her husband, so Cerynes and Phalces desperately abducted her. Cerynes and Phalces drove their chariot towards Argos, with Deiphontes following in a hot pursuit.

Deiphontes killed Cerynes with his arrow, but didn't want to harm his wife, because he might miss his aim at Phalces. So Deiphontes tried to close in them with his own chariot, hoping to pull her away. But Phalces pulled his sister back violently, which killed her.

Deiphontes and his children buried Hyrnetho in a grove of wild olive, near where she had fallen. They named the grove after Hyrnetho. The surviving children of Deiphontes and Hyrnetho were Antimenes, Xanthippus and Argeius, and a daughter named Orsobia.

According this, Deiphontes and his followers remained in Epidaurus, while Ceisus as king of Argos. But Medon, Ceisus's son succeeded him, they lost a lot of royal authority, that all Argive rulers were only kings in name only.

In Sparta, Procles and Eurysthenes found two houses, where generation after generation, Sparta would always have two kings, one from each house. Though they were twins, there was animosity and hatred between the two brothers. The two kings would exist to classical period of Greece, and rivalry between the two houses continued to exist until the Roman annexed Greece in 146 BC.

Like his brother in Argos, Cresphontes also didn't enjoy a long reign. Cresphontes moved the capital to Stenyclerus and married Merope, who bore him three sons, his youngest being Aepytus.

Another Heraclid, Polyphontes killed Cresphontes and his two elder sons, and took the throne of Messenia. Aepytus was saved, and raised by Cypselus, king of Arcadia. He had also forced Merope to marry him.

When Aepytus had grown to manhood, he returned to Stenyclerus, pretending that he had killed Aepytus. Polyphontes warmly received him as guest. Merope thinking that her husband's guest murdered her son, she would have murdered her own son in the guest room. Fortunately, Aepytus revealed his mother his real identity and together they planned to kill Merope's husband.

The next day, Polyphontes invited Aepytus to assist him in sacrificing a bull for the death of Cresphontes' son. Instead of killing the bull with an axe, Aepytus brought the weapon upon the usurper's head. Aepytus became the new ruler of Messenia.

Aepytus was quite a popular king, because he had given gifts to the poor, and showed deference to the nobles. The succession went smoothly, when Glaucus ascended after him.