What three events helped Sparta win the war with Athens?

Three key events that helped Sparta win the Peloponnesian War against Athens include the Sicilian Expedition (415-413 BCE), where Athens suffered a devastating defeat, significantly weakening its military resources. The construction of the Spartan naval fleet, aided by Persian support, allowed Sparta to challenge Athenian naval dominance effectively. Lastly, the decisive Battle of Aegospotami in 405 BCE resulted in a major Athenian defeat, leading to the blockade of Athens and ultimately forcing its surrender in 404 BCE.