The Delian League and the Athenian Empire

Patrick Quinn Quirke, Dickson College, 2012

The following essay was written as part of the Athens to Alexander unit at Dickson College, Semester 2, 2012. It was written in response to the following question: 'How did the Delian League evolve into the Athenian Empire?' Pat Quinn Quirke has also contributed The Birth of the Roman Navy to Clio.

The Delian League was formed as a defence pact against the Persians. Over time Athens slowly manipulated the League, using it to create its very own empire. This transformation can be seen in four distinct stages, first starting with the Athenian aggression shown towards the states that wished to secede from the League and their reduction to tribute paying subject states. Next Athens began to use the forces of the Delian League to assist in quarrels unrelated to the League, a clear sign that Athens was starting to use the League to further its own purposes. When Athens moved the Delian League treasury from the island of Delos to the Athenian Acropolis, claiming that it was in danger on Delos, it seems clear there was an ulterior motive relating to furthering an emerging Athenian Empire. From there, Athens began to use the funds from the League to pay for Athenian interests rather than those of the League states. Thus the Delian League evolved over time into the Athenian Empire.

Fragment of an Athenian decree concerning the collection of the tribute from the members of the Delian League, probably passed in the spring of 447 BC.
The Delian League was formed following the conclusion of the second Persian War in circa 477 BCE. The Second Persian War proved to be a decisive point in Greek history, with the Athenians now becoming the dominant naval power through their victory in the Battle of Salamis in 480 BCE. Although the victory was decisive, the Greek states felt that the Persian threat was still looming, thus they formed a mutual defence pact. With over 150 members from various city-states, the Delian League was formed with the treasury located on the island of Delos. Delos was chosen due to its significance in Ionian culture and religion, its central location between Athens and Asia Minor, and its political insignificance (Bradley, 1988, pg. 163; Laistner, 1970, pg. 5). Each city-state was required to contribute their naval force to the League. Those without ships would pay an annual fee (Laistner, 1970, pg. 6). As Athens had the largest naval power, they naturally became de facto leader of the Delian League.

Hornblower (2011, pg. 13), drawing on Thucydides’ History of the Peloponnesian War and Aristotle’s Athenian Constitution, gives us an understanding of the laws that made up the constitution of the Delian League: " have the same friends and enemies as Athens... not to refuse to serve in league campaigns... not to make ‘private wars’ on other league members... to provide ships... provide money instead..." Historians Bradley (1988), Hornblower (2011) and Rhodes (1992) tend to agree that the Delian League was a permanent organisation and when a member had joined they were not allowed to leave until the League had dissolved.

Athenian aggression towards several of the city-states that wished to secede from the League was the first sign that they were no longer using the League merely as a defence pact, but rather for their own imperialistic gain. In 469 BCE Naxos attempted to leave the League and then in 465 BCE Thasos attempted to leave. Although the motivation for the attacks differed, both states suffered similar fates and reveal the intentions of the Athenians in relation to the League.

Laistner (1970, pg. 10) and Robinson (1966, pg. 132) agree that the exact reasons for Naxos leaving the League in 469 BCE are unknown. It is possible that they believed the Persians to no longer be a threat, or they simply may not have wanted to commit themselves and their forces to the League anymore. Bradley (1988, pg. 169) claims that Naxos was one of the main ship-contributing members, and upon secession the Delian League, led by Athens, invaded Naxos and forced it back into the League. P.J. Rhodes (1992), a historian on Ancient Greek history at the University of Durham, provides an image of the invasion of Naxos, based on the subsequent treatment of Thasos. "Naxos will have been forced to remain in the League against its will, to demolish its city wall, to surrender its warships [presumably, to Athens], and to pay an indemnity and tribute; we need not suppose that Athenian interference went further than that." (Rhodes, 1992, pg. 43). As Hornblower (2011) claims, the members of the League were bound to fulfill their military commitment set out in the constitution at the League’s birth. Therefore it seems reasonable that the members did not want to allow Naxos to leave the League before it had fulfilled its duty. However, it seems unreasonable for Athens to have then made Naxos a tribute paying subject state. This is the first occurrence of a tribute rather than a fund being paid to the League, a distinct characteristic of an emerging empire. Of note is that Athens was at the head of the League, and thus in a sense was the recipient of the tribute.

In the case of Thasos, the reasons for wanting to leave the League are clear. Thasos attempted to leave after a conflict with Athens over the control of trading posts and mines on the Thracian mainland (Rhodes, 2008, p. 44). Subsequently Athens invaded Thasos in a three-year assault, drawing on the resources of the League (Bradley, 1988, pg. 170). Eventually Thasos surrendered and was forced by Athens to pull down their city walls, hand over their ships and mainland possessions, and pay an indemnity and tribute to the League (Rhodes, 2008, pg. 44). "Thasians in the third year of the siege rendered themselves to the Athenians upon condition to raze their walls, to deliver up their galleys, to pay both the money behind and for the future as much as they were wont, and to quit both the mines and the continent." (Thucydides; I, 101). Although the conflict was only between Athens and Thasos, Athens used the forces of the Delian League to support its assault on Thasos, furthering its own agenda. From this it can be gathered that Athens clearly had control of the operation of the League and had now started to manipulate the League’s working for its own benefits.

In 454 BCE the true intentions of Athens became more apparent. The Athenians had already exercised their control over their allies, through their treatment of Naxos and Thasos. The next step was to make Athens the centre of the Delian League, by moving the treasury from the island of Delos to Athens. To support the move of the treasury, Pericles claimed that it was in danger from Persian attack and that the treasury would be safe in Athens.

There is some truth in the threat of a Persian attack, as the Athenians and their allies had just suffered a naval defeat in Egypt against the Persians and Phoenicians. The result of the battle was a loss of more than two hundred ships for the Athenian forces (Thucydides; I, 109). But did this threaten the island of Delos? After all the Greco-Persian conflicts had been regular throughout the initial years of the League, and this had never caused the League to fear for the safety of the treasury. It may have been argued that with such a heavy loss of ships it would be harder to defend an island if an attack eventuated. Thus it could be reasoned that a mainland location such as Athens would allow for greater defence and protection of the treasury. On the surface such a move seemed justified, however, the subsequent actions by Athens suggest that while the disaster in Egypt provided a useful pretext for the move of the treasury, in reality Athens had a more ambitious intention for the Delian League.

It is also plausible that little to no convincing was needed of the Delian League. Each member of the Delian League had one vote and for a movement to be passed, a majority vote was required (Bradley, 1988, pg. 165). However, after the Athenian fueled assault on Thasos, we can assume that Athens had a reasonable stronghold over the workings and decisions within the League. Either the Athenian vote had been increased since the beginning of the League, or their power and public aggression towards the states allowed them to manipulate the vote.

Another characteristic that defines an empire is a tribute paid to the leader by all the provinces. Initially many of the member states paid money to the Delian League, which would help fund the workings of the League. However, eventually the nature of the payment changed. This is exemplified by the building program, which was initiated by Pericles in 449 BCE and funded by the money that had been given to the Delian League by its members. The buildings of the Athenian Acropolis were rebuilt to an excessive degree, with an estimated cost of four thousand to six thousand talents (Low, pg. 165, 2008). The response from several Athenians was negative, and we can assume that members of the Delian League were also hostile to the program, as Miletus and Aegina refused to pay the fund and Thasos did not pay the full amount (Bradley, 1988, 184). However, Pericles claimed that the money was rightfully owed to Athens. "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 defence, and kept off the barbarians from attacking them." (Plutarch, 75 CE). No amount of justification can change the fact that these actions were clearly not that of a League, but rather an empire. Member states were now being forced to fund Athens and its interests, rather than the collective interests of the Delian League. As such, the payment had now become a tribute paid to Athens from its subject states. In addition, Bradley (1988, pg. 184) notes that those states that refused to pay had to plead their case in the Athenian law courts. This is yet another indicator that the Athenians were in full control of the League, with matters within the League being resolved by their own legal system. By this stage it was clear that the Delian League was no longer a league between Greek states, unified against a common enemy, but rather a vehicle through which Athens could create and then control its own empire.

The evolution of the Delian League into the Athenian Empire occurred over thirty to forty years. While the League was initially established for the collective security of the member states, Athenian interests soon dominated. This can be seen in the reduction of states wishing to secede from the League to tribute paying subject-states; the use of the Delian League forces to assist in Athenian quarrels with other states; and the shift of the treasury from Delos to Athens. The final stage in the evolution was the use of the League resources to fund Athenian interests, and by 449 BCE funds paid to the League by member states had become little more than tributes paid to an empire.


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Bradley, P. 1988, Ancient Greece Using Evidence, Edward Arnold Australia, Australia
Bradley offers a comprehensive account of Greek history, with a chronological explanation of the Delian League. Bradley draws on many sources, both ancient and modern, making this source unbiased and reasonably accurate.

Gomme, A. 1945, A Historical Commentary on Thucydides, Oxford University Press, London
This source attempts to analyse Thucydides’ History of the Peloponnesian Wars. The text assumes considerable knowledge of Greek, however, it can help to further understand Thucydides’ works.

Hornblower, S. 2011, The Greek World 479-323 BC, Methuen & Co LTD, Oxon
Hornblower takes an analytical approach to the transformation of the Delian League into the Athenian Empire. The book is highly academic and at times the language is convoluted, however, he establishes strong points from analysing the writings of ancient historians and drawing his own conclusions.

Laistner, M. 1970, Greek World 479-323 BC, University Paperback, Northampton
Laistner gives a broad explanation of the Delian League from its inception through to its transformation into the Athenian Empire. While outlining the key events Laistner uses ancients sources such as Herodotus and Thucydides to support his claims.

Low, P. 2008, The Athenian Empire, Edinburgh University Press Ltd, Edinburgh
Low offers a detailed description of the Athenian Empire. In regards to the Delian League, Low provides detailed information on the tribute money, in regards to the amounts and how they changed over time.

P.J. Rhodes, The Cambridge Ancient History, Cambridge University Press,
This book is a compilation of historian’s works. Chapter three, written by P.J. Rhodes, looks at the Delain League in considerable detail. With the use of a variety of sources, this book proves valuable in understanding of the Delain League and the key events.

Robinson, C. 1966, A History of Greece, Methuen & Co LTD, London
Robinson gives a more detailed explanation of the Delian League, dedicating an entire chapter to the transformation from the Delian League to the Athenian Empire. Drawing from ancient and contemporary sources this source is reasonably unbiased.

Thucydides, History of the Peloponnesian War, translated by Thomas Hobbes, retrieved from <>
Thucydides is an ancient historian, who gives of a history of the Peloponnesian War. Thucydides was alive, albeit young, when some of the significant moments in the Delian League occurred. His histories are reasonably unbiased.