Upon succeeding his father, Suleiman began a series of military conquests, eventually leading to a revolt led by the Ottoman-appointed governor of Damascus in 1521. Suleiman soon made preparations for the conquest of Belgrade from the Kingdom of Hungary—something his great-grandfather Mehmed II had failed to achieve because of John Hunyadi's strong defense in the region. Its capture was vital in removing the Hungarians and Croats who, following the defeats of the Albanians, Bosniaks, Bulgarians, Byzantines and the Serbs, remained the only formidable force who could block further Ottoman gains in Europe. Suleiman encircled Belgrade and began a series of heavy bombardments from an island in the Danube. Belgrade, with a garrison of only 700 men, and receiving no aid from Hungary, fell in August 1521.