Aegospotamos (ē´gəspŏ´təməs), river of ancient Thrace flowing into the Hellespont. At its mouth in 405 BC occurred the culminating battle of the Peloponnesian War. Lysander and his Spartan fleet had come north to cut the grain supply of Athens. The Athenian fleet under Conon came to Aegospotamos and at first vainly tried to induce the Spartans to fight. Despite the warnings of Alcibiades, Conon and his men did not take proper precautions. Lysander fell upon them and completely destroyed the Athenian fleet.