At which battle in 425 BCE did Spartan soldiers surrender to Athens?

Spartan soldiers surrendered to Athens at the Battle of Sphacteria in 425 BCE.

During the Peloponnesian War, an Athenian force trapped Spartan hoplites on the island of Sphacteria, off the coast of Pylos in Messenia. After repeated fighting and a prolonged blockade, the Spartans capitulated rather than continue a hopeless defense.

The surrender shocked the Greek world because Spartan warriors were famous for refusing to yield. The prisoners were taken to Athens and used as leverage in negotiations. Their capture also threatened Sparta’s ability to protect its territory and its dependent population in Messenia.

The episode was not the final defeat of Sparta. The Peloponnesian War continued until 404 BCE, when Athens surrendered to Sparta. Sphacteria is important because it showed that even elite Spartan hoplites could be isolated and compelled to surrender.