The essence of the Peace of Nicias was a return to the pre-war situation: most wartime gains were to be returned. Most notably, Amphipolis would be returned to Athens, and the Athenians would release the prisoners taken at Sphacteria. Temples throughout Greece would be open to worshippers from all cities, and the oracle at Delphi would regain its autonomy. Athens could continue to collect tribute from the states as it had done so since the time of Aristides, but Athens could not force them to become allies. Athens also agreed to come to Sparta's aid if the Helots revolted. All of Sparta's allies agreed to sign the peace, except for the Boeotians, Corinth, Elis, and Megara.