Second Athenian League
The Second Athenian Empire or Confederacy was a maritime confederation of Aegean city-states from 378 BC-355 BC and headed by Athens primarily for self-defense against the growth of Sparta and secondly, the Persian Empire.
Origins
The formation of the confederacy was stimulated by the invasion of Attica by Sphodrias of Sparta and Sparta's refusal to prosecute him for his actions (according to Xenophon and Diodorus Siculus). It was extremely popular at first, with a number of states previously controlled by Sparta signing up as members. Sparta's increasing imperialism over the last decade and interference in her supposed allies' affairs was the main reason for the keenness for the large number of Greek states to become involved in the league. Coupled with this was Sparta's apparent disregard for the terms of the Peace of Antalcidas, which had stated that all Greek states other than those controlled by Athens (i.e. Lemnos, Imbros and Scyros) were to be autonomous.
The Decree of Aristoteles
An inscribed 'prospectus' for the league was found at Athens (Inscriptions Greques 2, 43, also known as the Aristoteles decree) dating to 377 BC, detailing the aims of the new league. The intention was to ensure that Sparta would allow all the Greeks to be autonomous; the states involved were all to have autonomy; and Athens was not permitted to own land in any of the states who were members, or to inflict upon them a garrison; they could also all have their own constitution, not necessarily a democracy. This 'prospectus' appears to try to promise that this league would not turn out the same way as the earlier, fifth century Delian League.
The Rise of Thebes
Sparta's interference and invasion of Thebes in 382 gave her a very good reason to join the league. However her behaviour within the league became difficult and Athens started to realise that Thebes was not necessarily to be trusted. For example, Thebes destroyed Plataea in 372, which had only recently been refounded. Athens started to think about negotiating peace with Sparta; it was while Athens was discussing this with Sparta that Thebes defeated the Spartan army conclusively at Battle of Leuctra (371BC).
Later History of the League
After Sparta's defeat in 371 BC by Thebes the original terms set out in the prospectus had been achieved, yet Athens did not want to give up her power over these states. A series of revolts ending with the Social War (357-355 BC) and the revolts of several of Athens' major allies finally put an end to the confederacy.
Further Reading
Cargill, Jack (1981). The Second Athenian League: Empire of Free Alliance? Berkeley: University of California Press. ISBN 0520040694 Rhodes, P.J. (2005). 'A History of the Classical Greek World, 478-323BC', Blackwell Publishing