In the 19th century the decline of the Ottoman Empire changed the geopolitical setting of the Balkans. Many nations that had lived under Ottoman rule for centuries would seek independence and eventually get it. One of these nations were the Serbs, and Serbia had been conquered by the Ottomans in 14th and 15th century. With nationalism on the rise in Europe, and a good amount of support from Russia Serbia gained its independence in 1878. While the Ottomans were falling back other Great Powers had been taking advantage lf this situation, and the Austro-Hungarian Empire had secured its interest in the region. In 1914 they had conquered the areas of modern day Croatia, Bosnia and some parts of Serbia. A large amount of ethnic Serbs were at the time living under Austro-Hungarian rule, and some of them wanted be a part young Serbian state.

This urge for a greater Serbia or a united Yugoslavia made people organize and fight for their right to unite with Serbia. One of these grpups were the "Black Hand", and they eventually carried out the assassination of Archduke Ferdinand. The purpose of the organization was to liberate Austro-Hungarian slavs, and some would see them as terrorists and others freedom fighters. But if we look at this from a Serbian perspective, the struggle against an invading imperial power were a fair and just couse. The Serbs had been ruled by others for centuries and this could not be tolerated anymore. In the spirit of this nationalistic ideology they were actually fighting for their compatriots. Ferdinand was the heir to the throne and the symbol of the Austro-Hungarian Empire, and hitting him would cause great instability in the Empire and maybe make pave the way to victory for the Serbs. The Serbians were right in their own minds, they were fighting for freedom. Nationlistic ideology mixed with ethnic complexity and tensions, were able to set some real solid foundation for instability in the Balkans. Fueled by their nationalistic hopes and dreams they accidentally paved the way for WW1. For some the Bosnian Serb Gavrilo Princip, a member of Young Bosnia, will be remembered as a hero and freedom fighter. For others a confused young and deluded man. And for others a murderer and a terrorist. But in our case from the Serbian perspective, this young man sacrificed his life so the nation could live on. The act was necessary and just in the struggle for freedom for the South Slavic peoples.

Note: I'am not pro or con Serbian nationalism and etc. I just wanted to illustrate the Serbian/South Slav perspective.

Sources:

Cassels, Lavender. The Archduke and the Assassin: Sarajevo, June 28th, 1914. Random House (UK), 1984.

Remak, Joachim. Sarajevo: the story of a political murder. Criterion Books, 1959.

Savich, Carl. "Gavrilo Princip and Patrick Pearse: Nationalism, Patriotism, and Rebellion: A Comparison." Preserve Serbian Heritage. Accessed April 20 (2016).

Sussex, Roland, and John Christopher Eade. Culture and nationalism in nineteenth-century Eastern Europe. Slavica Pub, 1985.