The Delian League was an association of fifth-century BC Greek city-states (approximately 150)[1] under the leadership of Athens, whose purpose was to continue fighting Persia after the Greek victory in the Battle of Plataea. According to Thucydides (1.96), the official aim of the League was to "avenge the wrongs they suffered by ravaging the territory of the king." In reality, this goal was divided into three main efforts - to prepare for future invasion, to seek revenge against Persia, and to organize a means of divvying spoils. League members swore to have the same friends and enemies, and dropped ingots of iron into the sea to symbolize the permanence of their alliance.