key event of 454 BC was the moving of the treasury of the Delian League from Delos to Athens. This is often seen as a key marker of the transition from alliance to empire, but while it is significant, it is important to view the period as a whole when considering the development of Athenian imperialism, and not to focus on a single event as being the main contributor to it. At the start of the Peloponnesian War, only Chios and Lesbos were left to contribute ships, and these states were by now far too weak to secede without support. Lesbos tried to revolt first, and failed completely. Chios, the most powerful of the original members of the Delian League save Athens, was the last to revolt, and in the aftermath of the Syracusan Expedition enjoyed success for several years, inspiring all of Ionia to revolt. Athens was nonetheless eventually able to suppress these revolts. To further strengthen Athens's grip on its empire, Pericles in 450 BC began a policy of establishing kleruchiai—quasi-colonies that remained tied to Athens and which served as garrisons to maintain control of the League's vast territory. Furthermore, Pericles employed a number of offices to maintain Athens' empire: proxenoi, who fostered good relations between Athens and League members; episkopoi and archontes, who oversaw the collection of tribute; and hellenotamiai, who received the tribute on Athens' behalf. Athens's empire was not very stable and after 27 years of war, the Spartans, aided by the Persians and Athenian internal strife, were able to defeat it. However, it did not remain defeated for long. The Second Athenian League, a maritime self-defense league, was founded in 377 BC and was led by Athens. The Athenians would never recover the full extent of their power, and their enemies were now far stronger and more varied. See also Athenian democracy Chalcis Decree Hellenic civilization Pentecontaetia Zone (colony) References Citations General sources Further reading External links Military history of ancient Greece League 5th-century BC military alliances 5th-century BC establishments 5th-century BC disestablishments Greek city-state federations Former confederations