Formation of the Delian League

Historical ruins in Athens, Greece

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Several Ionian cities joined together in the Delian League for mutual protection against the Persians. They placed Athens at the head (as hegemon) because of her naval supremacy. This free confederation (symmachia) of autonomous cities, founded in 478 B.C., consisted of representatives, an admiral, and treasurers appointed by Athens. It was called the Delian League because its treasury was located at Delos.


Formed in 478 B.C., the Delian League was an alliance of mainly coastal and Aegean city-states against Persia at a time when Greece feared Persia might attack again. Its goal was to make Persia pay and to free the Greeks under Persian dominion. The league morphed into the Athenian Empire that opposed the Spartan allies in the Peloponnesian War.

After the Persian Wars, which included Xerxes' invasion by land at the Battle of Thermopylae (the setting for the graphic novel-based movie ), the various Hellenic poleis (city-states) divided into opposing sides ranged around Athens and Sparta, and fought the Peloponnesian War.

This enervating war was a major turning point in Greek history since in the following century, the city-states were no longer strong enough to stand up to the Macedonians under Philip and his son Alexander the Great. These Macedonians adopted one of the aims of the Delian League: to make Persia pay. Strength is what the poleis had been seeking when they turned to Athens to form the Delian League.

Mutual Protection

Following Hellenic victory at the Battle of Salamis, during the Persian Wars, Ionian cities joined together in the Delian League for mutual protection. The league was meant to be offensive as well as defensive: "to have the same friends and enemies" (typical terms for an alliance formed for this dual purpose [Larsen]), with secession forbidden. The member poleis placed Athens at the head (hegemon) because of her naval supremacy. Many of the Greek cities were annoyed with the tyrannical behavior of the Spartan commander Pausanias, who had been leader of the Greeks during the Persian War.

Thucydides Book 1.96 on the formation of the Delian League

"96. When the Athenians had thus gotten the command by the confederates' own accord for the hatred they bare to Pausanias, they then set down an order which cities should contribute money for this war against the barbarians, and which galleys.
For they pretended to repair the injuries they had suffered by laying waste the territories of the king. [2] And then first came up amongst the Athenians the office of treasurers of Greece, who were receivers of the tribute, for so they called this money contributed.
And the first tribute that was taxed came to four hundred and sixty talents. The treasury was at Delos, and their meetings were kept there in the temple."

Members of the Delian League

In The Outbreak of the Peloponnesian War (1989), author-historian Donald Kagan says the members included about 20 members from the Greek islands, 36 Ionian city-states, 35 from the Hellespont, 24 from around Caria, and 33 from around Thrace, making it primarily an organization of the Aegean islands and coast.

This free confederation (symmachia) of autonomous cities, consisted of representatives, an admiral, and financial officers/treasurers (hellenotamiai) appointed by Athens. It was called the Delian League because its treasury was located at Delos. An Athenian leader, Aristides, initially assessed the allies in the Delian League 460 talents, probably annually [Rhodes] (there is some question about the amount and people assessed [Larsen]), to be paid to the treasury, either in cash or warships (triremes). This assessment is referred to as phoros 'that which is brought' or tribute.

"23.5 Hence it was Aristeides who assessed the tributes of the allied states on the first occasion, two years after the naval battle of Salamis, in the archonship of Timosthenes, and who administered the oaths to the Ionians when they swore to have the same enemies and friends, ratifying their oaths by letting the lumps of iron sink to the bottom out at sea."
— Aristotle Ath. Pol. 23.5

Athenian Supremacy

For 10 years, the Delian League fought to rid Thrace and the Aegean of Persian strongholds and piracy. Athens, which continued to demand financial contributions or ships from its allies, even when fighting was no longer necessary, became more and more powerful as her allies became poorer and weaker. In 454, the treasury was moved to Athens. Animosity developed, but Athens would not permit the formerly free cities to secede.

"The enemies of Pericles were crying out how that the commonwealth of Athens had lost its reputation and was ill-spoken of abroad for removing the common treasure of the Greeks from the isle of Delos into their own custody; and how that their fairest excuse for so doing, namely, that they took it away for fear the barbarians should seize it, and on purpose to secure it in a safe place, this Pericles had made unavailable, and how that 'Greece cannot but resent it as an insufferable affront, and consider herself to be tyrannized over openly, when she sees the treasure, which was contributed by her upon a necessity for the war, wantonly lavished out by us upon our city, to gild her all over, and to adorn and set her forth, as it were some vain woman, hung round with precious stones and figures and temples, which cost a world of money.'"
"Pericles, on the other hand, informed the people, that they were in no way obliged to give any account of those moneys to their allies, so long as they maintained their defense, and kept off the barbarians from attacking them."
— Plutarch's Life of Pericles

The Peace of Callias, in 449, between Athens and Persia, put an end to the rationale for the Delian League, since there should have been peace, but Athens by then had a taste for power and the Persians started supporting the Spartans to Athens' detriment [Flower].

End of the Delian League

The Delian League was broken up when Sparta captured Athens in 404. This was a terrible time for many in Athens. The victors razed the great walls linking the city to her harbor city of Piraeus; Athens lose her colonies, and most of her navy, and then submitted to the reign of the Thirty Tyrants.

An Athenian league was later revived in 378-7 to protect against Spartan aggression and survived until Philip II of Macedon's victory at Chaeronea (in Boeotia, where Plutarch would later be born).

Terms to Know

  • hegemonia = leadership.
  • Hellenic = Greek.
  • Hellenotamiai = treasurers, Athenian financial officers.
  • Peloponnesian League = modern term for the military alliance of the Lacedaemonians and their allies.
  • symmachia = a treaty where the signers agree to fight for one another.


  • Starr, Chester G. A History of the Ancient World. Oxford University Press, 1991.
  • Kagan, Donald. The Outbreak of the Peloponnesian War. Cornell University Press, 2013.
  • Holden, Hubert Ashton, "Plutarch's Life of Perciles," Bolchazy-Carducci Publishers, 1895.
  • Lewis, David Malcolm. The Cambridge Ancient History Volume 5: The Fifth Century BC., Boardman, John, Davies, J.K., Ostwald, M., Cambridge University Press, 1992.
  • Larsen, J. A. O. “The Constitution and Original Purpose of the Delian League.” Harvard Studies in Classical Philology, vol. 51, 1940, p. 175.
  • Sabin, Philip, "International Relations" in "Greece, the Hellenistic World and the Rise of Rome," Hall, Jonathan M., Van Wees, Hans, Whitby, Michael, Cambridge University Press, 2007.
  • Flower, Michael A. "From Simonides to Isocrates: The Fifth-Century Origins of Fourth-Century Panhellenism," Classical Antiquity, Vol. 19, No. 1 (Apr. 2000), pp. 65-101.
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Gill, N.S. "Formation of the Delian League." ThoughtCo, Apr. 5, 2023, Gill, N.S. (2023, April 5). Formation of the Delian League. Retrieved from Gill, N.S. "Formation of the Delian League." ThoughtCo. (accessed June 9, 2023).