From alliance to empire
The Athenian empire was not planned from the start, and the word “empire” is one that ancient writers, including Thucydides, applied to it, often critically. It began as a voluntary alliance of Greek states founded in 478 or 477 BCE, after the Persian invasions of 480 and 479 had been repelled, ending the main phase of the Greco-Persian conflict on Greek soil. Its stated aim was to continue the war against Persia and to compensate members for losses by taking Persian booty. Over the next few decades the alliance changed character, and by about 450 BCE most members were effectively subjects of Athens. How and why this happened is the subject of this article.
The founding of the League
The alliance is called the Delian League by modern writers because its meeting place and treasury were on the sacred island of Delos. Members were mostly island and coastal communities in the Aegean and western Anatolia, many of them Ionian Greeks who had been under Persian rule. The Athenian statesman Aristides is traditionally credited with assessing what each member should contribute. Larger states supplied ships, while smaller ones paid money. Thucydides says the first assessment was 460 talents a year, a figure that should be treated as traditional, as we have no independent record of it.
The fleet itself owed much to Themistocles, who had persuaded the Athenians before the invasion to spend a windfall from the Laurion silver mines on new warships, an episode sometimes described as Themistocles naval strategy. Athens commanded the fleet and appointed the treasurers, who were Athenians. That arrangement gave it enormous influence from the beginning, and it matters for what followed.
Compulsion, revolt and the change of treasury
The turning point came when members tried to leave. Thucydides reports that Naxos left the alliance in the 470s and was forced back by Athenian force, and that Thasos revolted around 465 and was besieged for about two years before surrendering. The terms commonly included losing walls and warships, paying tribute and sometimes a fine. As more members commuted their ship contribution into money, Athens’s navy grew while theirs withered, so that fewer of them could resist.
In about 454 BCE the treasury was moved from Delos to Athens, a step usually dated after a disastrous Athenian campaign in Egypt. From then on, Athens set aside a small share of each year’s payment for the goddess Athena, and fragments of the inscribed records, known as the tribute lists, survive. These stone lists are among the best evidence for the empire and let historians track which cities paid and how much.
The Delian League tribute that flowed to Athens was spent on the fleet, and it also supported public projects, a point made by critics at the time.
The tools of control
Athens used several means, varying from place to place.
- Tribute and the fleet. Annual payments funded the navy, and the Greek trireme, a fast oared warship, was the engine of Athenian power. Rowers were paid, which also tied large numbers of ordinary citizens to the empire’s success.
- Garrisons and officials. Some rebellious states received Athenian garrisons or resident officials.
- Cleruchies. Athenian citizens were settled on land taken from allies. They remained Athenian citizens, and the settlements served partly as military outposts.
- Courts and law. Certain legal cases involving allies were transferred to Athens, which increased the city’s authority in practice.
- Regime support. Athens often supported democratic governments in allied cities, though it also dealt harshly with those that resisted.
Allies also felt the weight of Athenian democracy, since decisions affecting them were made by an assembly in which they had no vote. The picture is not uniform. Some allies appear to have accepted the arrangement, since the fleet protected the sea lanes and ended Persian pressure. Others resented it deeply.
War with Persia ends, rivalry with Sparta grows
Fighting with Persia seems to have wound down by the middle of the century. Some ancient sources report a formal settlement, often called the Peace of Callias, but modern scholars disagree on whether such a treaty existed. After this point, the alliance’s original purpose looked thin, yet the payments continued. Its fortified link with the harbour at Piraeus, completed with the Long Walls, meant that Athens could not be starved by a land army so long as its navy held the sea.
Sparta and its allies watched with growing alarm. Fighting broke out between Athens and the Peloponnesians at various points in the 450s and 440s, and a Thirty Years’ Peace was agreed in 446/445 BCE. A revolt of Samos in 440 and 439 was suppressed after a long siege, and it showed again that Athens would use force against a member that wanted to leave.
The road to the Peloponnesian War
Thucydides argued that the underlying cause of the war that began in 431 BCE was the growth of Athenian power and the fear it caused in Sparta. Specific disputes, over Corcyra, Potidaea and a trade decree against Megara, triggered the conflict, but he regarded these as the immediate causes. Modern historians usually accept that structure while debating how much blame each side deserves.
The war lasted, with interruptions, until 404 BCE. Athens had attempted a major expedition to Sicily in 415, which ended in disaster by 413, and the loss of its fleet encouraged revolts among allies. Persia then provided money to Sparta, a reversal of the early league’s purpose. Athens surrendered in 404 BCE and its empire was dissolved. A smaller Second Athenian League formed in 378/377 BCE, with promises not to repeat the abuses of the first.
Judging the empire
Ancient views were mixed. Thucydides has Athenian speakers describe the empire as a tyranny that it would be dangerous to give up, while Pericles in his account stresses its achievements. The empire gave the city money for monuments and ships, and it also compelled other Greeks to pay for them. Both statements are true, and recognising that is the main point of the story.