In the 15th century the Montenegrin ruler Ivan Crnojević (1465–1490) was at war with the infiltrating Venetians. Unable to maintain war on both fronts, the Ottoman Empire had conquered much of Montenegro's territory and introduced Islam. Ivan's third son Staniša Crnojević was the first prominent Montenegrin of the Muslim faith, and since then Islam was not an uncommon religion to the Crnojević Montenegrin ruling dynasty.