v. (July 17-Sept. 12, 1683) Attempted capture of Vienna by Ottoman Turkey. On appeal from the Hungarian Calvinists to attack the Habsburg capital, the Turkish grand vizier, Kara Mustafa (1634-83), and his army of 150,000 laid siege to Vienna in July 1683, after capturing its outer fortifications. Pope Innocent XI convinced John III Sobieski of Poland to lead a combined army of 80,000 to relieve the siege. On Sept. 12, 1683, Sobieski, aided by Charles of Lorraine, led the attack from the surrounding hills and after 15 hours drove the Turks from their trenches around the city. Thousands were slaughtered or taken prisoner. The event marked the beginning of the decline of Turkish domination in eastern Europe