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The Delian League artwork

The Delian League

In Our Time: History

July 16, 2026

Misha Glenny and guests discuss the origins and evolution of an alliance which transformed the geopolitics of the classical world: the Delian League. Since the start of the 5th Century BCE, city states across Greece had been fighting a series of armed conflicts in the Greco-Persian Wars.

Speakers Misha Glenny, Paul Cartledge, Polly Low, Leah Lazar

TopicsHistory

Misha Glenny (0:00)

This is In Our Time from BBC Radio 4, and this is one of more than a thousand episodes you can find in the In Our Time archive. A reading list for this edition can be found in the episode description wherever you're listening. I hope you enjoy the program.

Hello. In 478 BCE, the Greco-Persian Wars had seen a series of armed conflicts for over 20 years. After the defeat of a second Persian invasion, a League of Cities across Greece came together. They formed a new alliance, led by Athens, an alliance which we now call the Delian League. In the following decades, Athens used the Delian League to grow its own wealth and formidable naval power. But cities who tried to leave the alliance found themselves violently put down and their lands confiscated. What began as a cooperative alliance, sworn to fight back and defend Greeks against the Persian Empire, gradually started to seem like it may have created another imperial power, the Athenian Empire.

With me to discuss the Delian League are Leah Lazan, lecturer in Hellenistic Culture at the University of Manchester, Polly Lowe, professor in the Department of Classics and Ancient History at the University of Durham, and Paul Cartledge, AG. Leventer's senior research fellow of Clare College, University of Cambridge. And Paul, it's to you I want to come first to give us if you can a sense of the geopolitical landscape of this period. What did Greece look like and what did the Persian Empire look like?

Paul Cartledge (1:46)

You started off in 478, so I'm going to take you back 70 plus years to about 550 And that's when the Persian Empire, sometimes we say the Achaemenid Persian Empire, rose very, very suddenly in, of course, Iran. Within 50 years, it had spread east-west, far east as Afghanistan, Pakistan, as far west as the Aegean Sea, and indeed slightly over into Europe. So we're dealing with a vast territorial empire, such as the Greeks, never were to know for quite a long time until after the period we're looking at. So what was Greece? Well, there was no such thing as a nation-state of Greece. There was a Kulturkreis, a German for a cultural circle, of Hellas, people who spoke Greek, thought Greek, behaved Greek, and they were spread all over the Mediterranean, all around the Black Sea.

So, no one focused, but the nearest bit of the Greek world to the Persians was actually within the Persian Empire. So, as the Persians expanded west in the second half of the Sixth Century BC, they conquered a whole string of Greek cities along the western seaboard of what is the Aegean Sea for the Greeks. You have, therefore, a confrontation potentially, a potential crunch point at the Aegean border of the western Persian Empire. But 50 years or so after they had first been incorporated in the Persian Empire, a bunch of Greeks decided they didn't want to be in the Persian Empire anymore. So, one particular Greek city, it's called Miletus, it's now in western Turkey, a representative went to mainland Greece seeking aid in order to support them militarily, that is principally with ships but also with men and money, in rising up against the Persian Empire.

The Athenians accepted and that is the beginning of the Greco-Persian Wars as seen from the mainland of Greece. If you're looking at it all from Iran, well these pesky Greeks on the far west of our Empire, do we need to worry about them? Well, the Persians eventually decided to launch a vast invasion, amphibian, in the late 480s and that resulted in what we call the Greco-Persian Wars and thereafter the Delian League.

Misha Glenny (4:23)

Okay, so why the name Delian League? It comes from the island of Delos where the alliance was established, but why was Delos, it's quite a small island, why was it chosen?

Paul Cartledge (4:35)

Well, it's a bit like the Holy Roman Empire, which Voltaire said was neither Holy nor Roman nor an Empire. So it was Delian only in the sense that the oaths of the initial allies, who some of them had been allied before, they're now new allies, they're meeting together to form a new alliance on the island of Delos. Delos is pretty much bang in the middle of what in Greek is Kiklades, we say the Cyclades in the central Aegean. And it belongs to the bit of the Greek culture, which we call Ionian, because that's the way in which they spoke Greek and the cults that they shared in common. For example, a festival called the Aperturia.

So Athens is the principal lead on this. It is going to be the lead ally.

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