The Lion of Damascus (1942)

In 1571 during the Ottoman–Venetian War, an Allied fleet is sailing to relieve besieged city of Famagusta. Its commander's young son is kidnapped and will only be freed if the city surrenders. A Turkish captain, known as the Lion of Damascus - is disgusted by this and changes sides and assists the rescue of the child. The allies win a major victory at the Battle of Lepanto.