According to the Homeric legend, on their way back to Ithaca after the end of the Trojan War, Ulysses and his ship crew were taken hostage by the Cyclop Polyphemus (son of Poseidon) who lived in the large cave opposite that of Ai Giannis, on Iraklia.He imprisoned them in his cave, where he also kept his sheep.
Resourceful as he was, Ulysses quickly devised an escape plan. He and his mates blinded Polyphemus’ single eye and made a getaway out of the cave by hanging from the underbelly of the sheep. They ran to their ship, which was anchored at Iraklia’s southwestern bay, Alimia, and raised the sails.
When Polyphemus got wind of all this, he started throwing huge rocks, hoping to sink the ship. He missed the target and the rocks are known today as the The Big Avelas and The Small Avelas islets, or Avelonissia.
Iraklia, like the other Small Cyclades islands, was already inhabited in the prehistoric age and has kept its name since antiquity.
Remains of two settlements and a cemetery dating to the 3rd millennium have been found at the locations of Kampos Agiou Athanassiou and Agios Mamas, while sanctuaries of the goddess Tyche (Fortune) and Lofitis Zeus have been identified in the Kampos area.
Tools made of obsidian –a volcanic rock material originating in Milos, in the western Cyclades- and found in various parts of Iraklia testify to the island’s participation in the region’s commercial activity during the Protocycladic period (3rd millennium).
Although the ruins of the fort on Kastro hill have not been precisely dated, they include traces of habitation during Hellenistic and Roman times.
During Ottoman times, Iraklia’s narrow and inaccessible coves became ideal hideouts for pirates, whose threat largely determined the everyday life and habits of the inhabitants.
In the 16th century, Iraklia came under the ownership and administration of the Monastery of Chozoviotissa, in the nearby island of Amorgos.After Greek independence in the 1820’s, Amorgiots signed 10-year contracts with the monastery allowing them to settle on Iraklia, cultivate the land and keep 50% of the produce.
This regime survived well into the 20th century, when the tenants were given permanent ownership of the land, leaving a small part to the monastery for the needs of the monks.
A clandestine radio was operated on Iraklia during the Axis occupation of World War II, transmitting valuable messages about German naval activity to the British headquarters in Cairo.