Kingdom of Serbia, 1912
The Principality of Serbia had become a Kingdom in 1882 under Milan Obrenović IV. On 18 October 1912 it declared war on the Ottoman Empire, but had already sent troops before that into Kosovo. Although meeting stiff resistance from Kosovar Albanians, they occupied the country, destroying and massacring Albanian villages, reaching Prishtina on 22 October. After the First Balkan War of 1912, Kosovo was internationally recognised as a part of Serbia at the Treaty of London in May 1913.