The effects of The Great War may still be in our and European countries today. Most of the immediate effects might have been resolved in the years passed The Great War. However, after about three decades after World War One ended, another world war was about to beHistorians have always debated on the causes of the Great War (WW1). However, Nationalism was the key cause of world war one. .
Serbian Nationalism was behind the death of Archduke Franz Ferdinand. The "Black Hand" was a terrorist group that supported Serbian Nationalism. It wanted to gain back Bosnia from Austro-Hungarian rule. Austria-Hungary opposed this union, so to draw attention to the issue of Bosnian sovereignty, "Black Hand" activist Gavrilo Princip, kills Archduke Franz Ferdinand (future leader of Austria-Hungary) and his wife (the duchess) Sophia. Austria-Hungary, considering how it's upcoming leader was brought down, saw this as a possibility to capture Serbia, and blamed the assault on the Serbian Government. So, Austria-Hungary sent an ultimatum to Serbia, stating three key demands, one, to put down all nationalist detestation against Austria-Hungary, two, castigate all those involved in the assassination plot, and three to allow Austro-Hungarian officials into Serbia to help crush the "Black Hand". The Serbian government accepted all demands except for the last one. Austria-Hungary took this as a complete refusal of the ultimatum, and declared war on Serbia on 26 July 1914. Overall, neglecting Bosnian independence cost Austria-Hungary its future leader.
The attack on the heir to the throne of Austria-Hungary threatened Austria-Hungary's Nationalism. The assassination of their future Archduke resulted in the collapse of nationalism in Austria-Hungary. So to redeem their superiority, Austria-Hungary declared war on Serbia. Despite the loss of pride, Austria-Hungary saw the declaration as a revenge, to get back at Serbia.