The man in the photograph is a Serb by the name of Gavrilo Princip. He was refused enrollment into the Serbian Army because of his short stature. He felt he needed to prove his courage and decided to assassinate the heir to the Austrian Empire the same year during the visit of Archduke Franz Ferdinand and his wife to Serbian Sarajevo on June 28, 1914. That started a chain reaction.
Austria declared war on Serbia! Russia was furious and declared war on Austria, which angered Germany and led it to declare war on Russia. France felt enraged and declared war on Germany. Germany responded by attacking France and entered Belgium. That led to Belgium’s and Britain’s fury and their declaration of war on Germany. The Ottoman authorities were appalled at their attack on Germany and declared war against them all. That resulted in the generalized anger of America, Italy, Greece, Romania, and Portugal against the Ottomans, and their collective declaration of war.
The First World War thus started in 1914 which caused the death of 16 million people, the disappearance of 8 million, in addition to 20 million wounded.
All this because of a man by the name of Gavrilo Princip who wanted to prove his courage despite his short stature and went ahead and assassinated Archduke Franz Ferdinand and lit the fuse to the Great War.
One can always find someone who is willing to burn an entire country to light his own cigarette… but Gavrilo Princip was willing to burn the world for his own purposes.