The Battle of Lepanto was a naval engagement that took place on 7 October 1571 when a fleet of the Holy League, a coalition of Catholic states (comprising Spain and its Italian territories, several independent Italian states, and the Sovereign Military Order of Malta) promoted by Pope Pius V to rescue the Venetian colony of Famagusta on the island of Cyprus (besieged by the Turks in early 1571) inflicted a major defeat on the fleet of the Ottoman Empire in the Gulf of Patras. All members of the alliance viewed the Ottoman navy as a significant threat, both to the security of maritime trade in the Mediterranean Sea and to the security of continental Europe itself.

The victory of the Holy League is of great importance in the history of Europe and of the Ottoman Empire, marking the turning-point of Ottoman military expansion into the Mediterranean, although the Ottoman wars in Europe would continue for another century. It has long been compared to the Battle of Salamis, both for tactical parallels and for its crucial importance in the defense of Europe against imperial expansion. It was also of great symbolic importance in a period when Europe was torn by its own wars of religion following the Protestant Reformation.