Explanation:
1. **Battle of Syracuse (413–415 BCE):** Athens launched a disastrous expedition against the city-state of Syracuse in Sicily. The campaign ultimately failed due to strategic errors and naval defeats, significantly weakening the Athenian forces and diminishing their naval power.
2. **Battle of Amphipolis (422 BCE):** This battle took place between Athens and Sparta. The Athenians, led by Cleon, suffered a significant defeat, resulting in the loss of the strategic city of Amphipolis. This event contributed to a period of relative instability and shifting alliances in the later years of the war.
3. **Battle of Aegospotami (405 BCE):** This naval battle was a decisive confrontation where the Spartan fleet, commanded by Lysander, defeated the Athenian fleet led by Conon. The victory led to the blockade of Athens' port, Piraeus, forcing Athens to surrender. This marked the end of the Peloponnesian War, with Sparta emerging as the dominant power in Ancient Greece.
