The Peloponnesian War was a conflict fought between the city-states of Athens and Sparta from 431 to 404 BCE. It was primarily a struggle for power and dominance in ancient Greece, involving various allies on both sides. The war is divided into three phases: the Archidamian War, the Sicilian Expedition, and the Ionian or Decelean War. The war ended with the defeat of Athens, leading to the establishment of Spartan hegemony in Greece. The conflict had significant consequences, including the weakening of Greek city-states and paving the way for the rise of Macedonia under Philip II.