In the political field the contribution of Aristidis was decisive in the growth of the alliance of Delos, with which the Athenians substantially offered their protection in the Ionian cities and in the islands.
The alliance was a form of agreement on the joint confrontation of exterior dangers.
After the midean wars and on the occasion the tyrannical behaviour of the king of Sparta towards the other Greek cities, they proposed to the Athenians to undertake the foundation and the hegemony of the alliance of Delos (478 b.c.), which constituted the most important Athenian success up to then for their appointment in sovereign Greek city.
The importance however for the appointment of the hegemonic role of Athens was decisive, because through the acceptance of the methods of payment of money instead of the military contribution, they helped Athens economically and gave the her the chance to develop an enormously equipped program.
At the same time they were changed, particularly after the transportation of funds from Delos to Athens, to tributary cities.
The effect of the money fund also encouraged however the internal political developments in Athens. The organisation of alliance was supported on the basis of autonomy of cities and aimed to the release of Greek cities from the Persian dominance. In the alliance most of the cities of Small Asia, Elisponto and Propontida were later included.