Part 3 introduces Alcibiades, an Athenian statesman who defects to Sparta and becomes an adviser and strategist. In particular, he suggests that Sparta takes the war to Syracuse, in Sicily, during which Athens suffers a major blow (including the capture of their entire expeditionary force). The Spartan Lysander, chief of its naval forces, begins to rise in power, and he eventually defeats the Athenian navy (which enables him to blockade Athens) and finally ends the war by successfully invading and subjugating Athens. Agesilaus, who becomes one of the kings of Sparta, finally sees Sparta become the dominant power in Greece. But decadence and corruption follow, along with a drastic reduction in Spartan citizens. These facts eventually lead to an irreversible decline in Sparta's fortunes, leading to war with Thebes, and, in 371 BC, the end of Spartan preeminence after the battle of Leuctra.
