Battle of Mantinea
In the war, Elis sided at first with Sparta. But Sparta, jealous of the increasing prosperity of its ally, availed itself of the first pretext to pick a quarrel. At the Battle of Mantinea (418 BC), the Eleans fought against the Spartans, who later took vengeance upon them by depriving them of Triphylia and the towns of the Acroreia.