<P> Friction between Athens and the Peloponnesian states, including Sparta, began early in the Pentecontaetia; in the wake of the departure of the Persians from Greece, Sparta attempted to prevent the reconstruction of the walls of Athens (without the walls, Athens would have been defenseless against a land attack and subject to Spartan control), but was rebuffed . According to Thucydides, although the Spartans took no action at this time, they "secretly felt aggrieved". Conflict between the states flared up again in 465 BC, when a helot revolt broke out in Sparta . The Spartans summoned forces from all of their allies, including Athens, to help them suppress the revolt . Athens sent out a sizable contingent (4,000 hoplites), but upon its arrival, this force was dismissed by the Spartans, while those of all the other allies were permitted to remain . According to Thucydides, the Spartans acted in this way out of fear that the Athenians would switch sides and support the helots; the offended Athenians repudiated their alliance with Sparta . When the rebellious helots were finally forced to surrender and permitted to evacuate the state, the Athenians settled them at the strategic city of Naupactus on the Corinthian Gulf . </P> <P> In 459 BC, Athens took advantage of a war between its neighbors Megara and Corinth, both Spartan allies, to conclude an alliance with Megara, giving the Athenians a critical foothold on the Isthmus of Corinth . A fifteen - year conflict, commonly known as the First Peloponnesian War, ensued, in which Athens fought intermittently against Sparta, Corinth, Aegina, and a number of other states . For a time during this conflict, Athens controlled not only Megara but also Boeotia; at its end, however, in the face of a massive Spartan invasion of Attica, the Athenians ceded the lands they had won on the Greek mainland, and Athens and Sparta recognized each other's right to control their respective alliance systems . The war was officially ended by the Thirty Years' Peace, signed in the winter of 446 / 5 BC . </P> <P> The Thirty Years' Peace was first tested in 440 BC, when Athens' powerful ally Samos rebelled from its alliance with Athens . The rebels quickly secured the support of a Persian satrap, and Athens found itself facing the prospect of revolts throughout the empire . The Spartans, whose intervention would have been the trigger for a massive war to determine the fate of the empire, called a congress of their allies to discuss the possibility of war with Athens . Sparta's powerful ally Corinth was notably opposed to intervention, and the congress voted against war with Athens . The Athenians crushed the revolt, and peace was maintained . </P> <P> The more immediate events that led to war involved Athens and Corinth . After suffering a defeat at the hands of their colony of Corcyra, a sea power that was not allied to either Sparta or Athens, Corinth began to build an allied naval force . Alarmed, Corcyra sought an alliance with Athens, which after debate and input from both Corcyra and Corinth, decided to swear a defensive alliance with Corcyra . At the Battle of Sybota, a small contingent of Athenian ships played a critical role in preventing a Corinthian fleet from capturing Corcyra . In order to uphold the Thirty Years' Peace, however, the Athenians were instructed not to intervene in the battle unless it was clear that Corinth was going to press onward to invade Corcyra . However, the Athenian warships participated in the battle nevertheless, and the arrival of additional Athenian warships was enough to dissuade the Corinthians from exploiting their victory, thus sparing much of the routed Corcyraean and Athenian fleet . </P>

Who was the king of athens during the peloponnesian war