The Battle of Egos was a battle fought in the Peloponnesian War between Athens and Sparta. It took place in 425 BC and was a decisive victory for Sparta. The battle was fought on the island of Sphacteria, off the coast of Pylos, and resulted in the surrender of the Athenian forces. The Spartans were able to capture more than 300 Athenian soldiers, which was a major blow to the Athenian army. This battle marked the beginning of the end of the Peloponnesian War, as it showed the superiority of the Spartan forces.