In 1858, one of the major Montenegrin victories over the Ottomans occurred at the Battle of Grahovac. Grand Duke Mirko Petrović, elder brother of Knjaz Danilo, led an army of 7,500 and defeated the numerically superior Ottomans with 15,000 troops at Grahovac on 1 May 1858. This forced the Great Powers to officially demarcate the borders between Montenegro and Ottoman Empire, ''de facto'' recognizing Montenegro's independence.