デロス同盟
Ever since the formation of the Delian League in 477 BC, the island of Melos had refused to join. By refusing to join the League, however, Melos reaped the benefits of the League without bearing any of the burdens. In 425 BC, an Athenian army under Cleon attacked Melos to force the island to join the Delian League. However, Melos fought off the attack and was able to maintain its neutrality. Further conflict was inevitable and in the spring of 416 BC the mood of the people in Athens was inclined toward military adventure. The island of Melos provided an outlet for this energy and frustration for the military party. Furthermore, there appeared to be no real opposition to this military expedition from the peace party. Enforcement of the economic obligations of the Delian League upon rebellious city-states and islands was a means by which continuing trade and prosperity of Athens could be assured. Melos alone among all the Cycladic Islands located in the south-west Aegean Sea had resisted joining the Delian League. This continued rebellion provided a bad example to the rest of the members of the Delian League.