The reasons behind World War I, which started in The Balkans in late July 1914, are numerous. Political, territorial, and economic conflicts among the major European powers in the forty years before the war were some of these reasons. Other factors included militarism, a complicated system of alliances, imperialism, and nationalism. The war started because of the choices made by leaders and military officials during the July Crisis of 1914. This crisis was triggered by the assassination of Archduke Franz Ferdinand and his wife Sophie by Gavrilo Princip, a Serbian nationalist from the group Young Bosnia. The Black Hand, a nationalist organization in Serbia, supported this group. The crisis happened following a lengthy and challenging sequence of diplomatic conflicts between the Great Powers (Italy, France, Germany, Britain, Austria-Hungary, and Russia) regarding European and colonial matters in the years leading up to 1914, which had escalated tensions. These public disputes can be linked back to shifts in the power dynamics in Europe since 1867. The war started mainly because of the tensions over land in the Balkans. Austria-Hungary, Serbia, and Russia were all vying for control and power in that area, which eventually led to the involvement of other major countries due to their alliances and treaties.