The First Messenian War was a war between Messenia and Sparta. It began in 743 BC and ended in 724 BC, according to the dates given by Pausanias.
The war continued the rivalry between the Achaeans and the Dorians that had been initiated by the purported Return of the Heracleidae. Both sides utilized an explosive incident to settle the rivalry by full-scale war. The war was prolonged into 20 years. The result was a Spartan victory. Messenia was depopulated by emigration of the Achaeans to other states. Those who did not emigrate were reduced socially to helots, or serfs. Their descendants were held in hereditary servitude for centuries, until the collapse of the Spartan state in 370 BC.