Nationalism in the Balkans helped contribute to the outbreak of WWI. Beginning in the late 19th century, the social unrest in the Balkan States became the focal point of many European powers. The Balkan peninsula was that of great importance due to its territorial and economic significance; however, the Balkan States consisted of many proud ethnic cultures who did not wish to be ruled by any authority other than themselves. The unification of other countries and strong patriotism fueled the desires of the Slavs, Greeks, Montenegrins, Rumanians, and Bulgarians to gain independence and revenge for the occupation of their lands by the Turks. This revolution sparked by strong nationalistic views led to the second largest war in human existence.
Up until the early 20th century, the Balkan States were controlled by the Ottoman Empire; however, due to the decline of their power and prestige, the Balkan States found an opportunity to gain independence. The unification and formation of Italy and Germany as countries encouraged the Balkan revolt of 1875-8. The revolt spread like wild fire through the Balkan peninsula and with the aid of Russia, Turkey was defeated. Through this, the Balkan States: Serbia, Montenegro, and Rumania, gained increases in their land; thus, resulting in a stronger patriotic pride. Turkey, however, still controlled parts of the Balkans and this angered Balkan nationalism because they now felt capable of governing themselves.
In 1885, the Bulgarian population of Eastern Rumelia revolted against Turkish rule and declared its union with Bulgaria . The Serbs became furious and proclaimed war because they felt threatened by this act. Surprisingly the Bulgarians proved to be a greater match for the Serbs and in the battle of Slivnitza, they were defeated. Britain agreed to the unification of Eastern Rumelia and Bulgaria and the Balkan States again gained more power through their nationalistic ideologies.
Religious tensions in Crete added to the possibility of war with a revolt in 1897 against Turkey. Due to the murders of both Muslims and Christians on the island, Crete and Greece declared war on Turkey. They were swiftly defeated within two weeks; however, because of the intervention of European powers, Turkey was forced to give up its possessions on the mainland. The Cretan revolt added to Balkan nationalism in this era and led the way for the formation of the Balkan League.