According to Thucydides, the cause of the war was the "fear of the growth of the power of Athens" throughout the middle of the 5th century BC. After a coalition of Greek states thwarted an attempted invasion of the Greek peninsula by the Persian empire, several of those states formed the Delian league in 478 BC in order to create and fund a standing navy which could be used against the Persians in areas under their control. Athens, the largest member of the league and the major Greek naval power, took the leadership of the league and controlled its treasury. Over the following decades, Athens was able to convert the Delian league into an Athenian empire. This increase in Athenian military power allowed it to challenge the Lacedaemonians (commonly known as the Spartans), who, as leaders of the Peloponnesian League, had long been the sole major military power in Greece.…
