History and Legend
A large Early Helladic II settlement on the northeast coast shows that the island (or peninsula, as it then was) played an important role in the Saronic area as early as the mid 3rd millennium bc. Late Mycenaean settlement is also evident both on the islet of Modi to the east of Poros, and at the site now occupied by the sanctuary of Poseidon on the central heights of the island. According to Pausanias (De scrip. II 33, 2), Calauria (the ancient city of the island) was originally sacred to Apollo at the time when Delphi was sacred to Poseidon; the gods then agreed to exchange possession of the two places. Both Delphi and Calauria went on subsequently to become important centres of ‘amphyctionies’ or sacred confederations. On Poros the cult of Poseidon was of primary importance and the island became the focus of the Calaurian League—an association of important cities which included Athens, Aegina, Epidauros, Hermione, Nauplia, Orchomenos in Boeotia, Prasai in Attica, and the nearby city of Troezen to whose territory the island belonged. The sanctuary of Poseidon at Calauria offered asylum; Demosthenes when pursued by Macedonian agents of Antipater, sought refuge here in 322 bc before committing suicide. In Late Antiquity an earth quake caused subsidence of the land, and the sea channel between the Peloponnesian coast and Poros was formed.
The island knew a period of growing prosperity after it was settled by Orthodox Albanians in the 17th century. In 1828, plenipotentiaries from France, Russia and Britain met on Poros to settle the terms and basis of the new kingdom of Greece in the so-called ‘Protocol of Poros’. Three years later, the independent islanders, under the leader ship of Hydra, took up an attitude of open hostility to the government of Capodistrias and established a ‘Constitu tional Committee’. The national fleet of Greece, including the frigate Hellas, its flagship, and the steamship Karteria, lay in Poros harbour. Capodistrias gave orders for them to be made ready to blockade Hydra; but Admiral Miaoulis, acting under the orders of the Hydriot government, preempted the move by seizing the fleet and the arsenal. On 1 August 1831, however, Miaoulis was overpowered by combined Russian and Greek forces. In the skirmish, he blew up the flagship Hellas, and the corvette, Hydra, rather than hand over the fleet to Russian Admiral, Pyotr Ivanovich Richord, as had been demanded.
Poros Island is part of the Argosaronic Island Group, Greece.