The Battle of Leontinoi was a minor engagment during the First Syracusan War between the city-state of Athens and Syracuse. Following a series of victories by the Athenian Army, a compex system of alliances triggered a Theban intervention in the war. Roughly half of the Athenian force was forced to return home to defend the Athenian homeland, leaving the expediton force unable to continue their campaign. The move demoralized the Athenian army, that attempted to pursue a retreating Syracusan force, but blundered in their attempts. Following a series of Syracusan re-supplying efforts, the Syracusan army turned around and defeated the Athenians near Leontinoi. The defeat was not decisive, and the Syracusans were unable to follow up, but the Athenian advance was grinded to a halt, and the first defensive line was constructed by the Athenians.