World War I was a complicated conflict and its origins are related to events that occurred in the 19th century such as the Scramble for Africa, wars that were loose by some countries such as German and France (Franco-Prussian War), and the spirit of nationalism that was burning in the hearts of the marginalized countries (Pan-Germanism and Rrevanchism). The trigger of this conflict was the murder of Francisco Ferdinando, prince of the Austro-Hungarian Empire, during his visit to Sarajevo (Bosnia-Herzegovina). The investigations led to the criminal: a young man from a Serbian group called "Black Hand", opposed to the influence of the Austro-Hungarian Empire in the Balkans. The Austro-Hungarian Empire did not accept the measures taken by Serbia in relation to crime and, on July 28, 1914, declared war on Serbia.
