Some years earlier Cleisthenes' family had won the contract to rebuild the Oracle at Delphi after a fire destroyed the temple. Thanks to Cleisthenes' generosity the new temple had been finished in marble, far exceeding the terms of the contract. Cleisthenes is supposed to have used the influence of this good deed to persuade the oracle's priestess, called the Pythia, to instruct Spartan envoys to 'free Athens.'

By lucky coincidence, the tyrant Hippias had also recently struck up an alliance with the city of Argos, Sparta's longest-standing enemy. So the Spartans also had good reasons of their own for seeing an end to Hippias.