The Spartan king Agis II invaded Argive territory after a pro-Spartan faction at Argos was evicted by an Athenian force under Alcibiades, whose mission was to establish democracy there.
[1] Agis did not manage to take the city of Argos but destroyed the walls that the Argives had begun to extend towards the sea.
[2] The campaign is described by the historians Thucydides (5.83.2), who actually fought in the war, and Diodorus Siculus (12.81.1), who wrote in the 1st century BC, over two hundred years later.
The Spartans did, however, capture and destroy the Argive town of Hysiae, taking all the male citizens as hostages.
In response, Athens dispatched a force of 40 triremes and 1,200 hoplites who fought the Battle of Orneae to remove the garrison and take the city.