Pentecontaetia

Pentecontaetia (Greek: πεντηκονταετία, "the period of fifty years") is the term used to refer to the period in Ancient Greek history between the defeat of the second Persian invasion of Greece at Plataea in 479 BC and the beginning of the Peloponnesian War in 431 BC. The term originated with a scholiast commenting on Thucydides, who used it in their description of the period. The Pentecontaetia was marked by the rise of Athens as the dominant state in the Greek world and by the rise of Athenian democracy, a period also known as Golden Age of Athens. Since Thucydides focused his account on these developments, the term is generally used when discussing developments in and involving Athens.

Shortly after the Greek victory of 479 BC, Athens assumed the leadership of the Delian League, a coalition of states that wished to continue the war against Persia. This league experienced a number of successes and was soon established as the dominant military force of the Aegean. Athenian control over the league grew as some "allies" were reduced to the status of tribute-paying subjects and by the middle of the 5th century BC (the league treasury was moved from Delos to Athens in 454 BC) the league had been transformed into an Athenian empire. Athens benefited greatly from this tribute, undergoing a cultural renaissance and undertaking massive public building projects, including the Parthenon; Athenian democracy, meanwhile, developed into what is today called radical or Periclean democracy, in which the popular assembly of the citizens and the large, citizen juries exercised near-complete control over the state.

The later years of the Pentecontaetia were marked by increasing conflict between Athens and the traditional land powers of Greece, led by Sparta. Between 460 BC and 445 BC, Athens fought a shifting coalition of mainland powers in what is now known as the First Peloponnesian War. During the course of this conflict, Athens gained and then lost control of large areas of central Greece. The conflict was concluded by the Thirty Years' Peace, which lasted until the end of the Pentecontaetia and the beginning of the Peloponnesian War.

The eventual breakdown of the peace was triggered by increasing conflict between Athens and several of Sparta's allies. Athens' alliance with Corcyra and attack on Potidaea enraged Corinth, and the Megarian Decree imposed strict economic sanctions on Megara, another Spartan ally. These disputes, along with a general perception that Athenian power had grown too powerful, led to the breakdown of the Thirty Years Peace; the Peloponnesian War broke out in 431 BC.

479—Rebuilding of Athens: Although the Greeks were victorious in the Persian War, many Greeks believed that the Persians would retaliate. This led Athens to rebuild its city walls that were razed by the Persian Army during the occupation of Attica in 480.

478—Formation of the Delian League: Athens and other city states form a coalition against Persia.

477—The Conquest of Eion: Cimon, the son of Miltiades of Marathon fame, led Athens to numerous victorious campaigns and war profits. In 477, he led an army against Persian-occupied Eion in northern Greece. Athens was able to benefit from this invasion since the region was rich in timber, which was critical to building Athens' burgeoning naval fleet.

476—The Conquest of Scyros: The invasions continued with success on a par with Cimon's prior campaigns. In 476, Athens fought against the pirates of Scyros, as the Delian League wanted to reduce piracy around the region and capture the important materials for itself.