How World War One began still fascinates many historians. Austro-Hungarian archduke Franz Ferdinand was assassinated in Sarajevo in 1914 and that incident is believed to have sparked the global conflict. But many facts about the assassination and its aftermath were obscured at the time. Our correspondent Aljosa Milenkovic was in the Balkans, trying to uncover some hidden truths about the start of The Great War.  

Tourist groups are regularly visiting this place in Sarajevo, the capital of Bosnia and Herzegovina.

They are told by their guides that World War One started right here on June 28, 1914, at the exact spot they are standing.

MUAMER FAZLIC SARAJEVO MUSEUM "There were two assassination attempts on that day. First by Nedeljko Cabrinovic, at the bridge 150 meters from here. He threw a hand grenade at the archduke's motorcade. Franz Ferdinand was not injured, and the visit continued as planned, despite security requests to abort it. On the way back, his driver took a wrong turn exactly where Gavrilo Princip was standing."

Princip drew his pistol at that moment and fired two shots at the Austro-Hungarian heir.

Those shots killed both Ferdinand and his wife.

The assassin was arrested on the spot, and soon after, the neighboring, small Kingdom of Serbia was accused of plotting the murder. An unstoppable string of events started unraveling.

ALJOSA MILENKOVIC SARAJEVO "For 104 years, Sarajevo has lived in the shadow of the event, that according to some historians, sparked World War One. While nobody can dispute the fact that Gavrilo Princip assassinated archduke Franz Ferdinand in this very city, the differing opinions about what actually caused the Great War are much more conflicting."

Some historians claim that this assassination was used as an excuse for the Austro-Hungarian empire to start a war against Serbia.

They argue that a few years earlier, when Elisabeth, the Empress of Austria, was assassinated, it did not lead to any military conflict.

Milos Skundric is a film director who spent 5 years researching for his documentary about the beginning of World War I.

He says that it was a perfect excuse for sending an ultimatum which Serbia could not accept.

MILOS SKUNDRIC DIRECTOR OF DOCUMENTARY 'THE LONG ROAD TO WAR' "It was well known that Leopold Berchtold, the Austrian foreign minister could not sleep because he was afraid that the ultimatum was so weak that Serbians could accept it. So, he was constantly changing the ultimatum. He wanted Serbia not to accept it and he wanted a war against Serbia. The Austrian Empire wanted a war against Serbia."

Back in 1914, Bosnia was under Austro-Hungarian rule, and almost half of its population were Serbs.

After Ferdinand's assassination, Muslim and Croat minorities who were supporters of the Empire, started pogrom against the Serbs, destroying their properties and killing many.

Gavrilo Princip, a Bosnian Serb was sentenced to 20 years in prison, as he was under age at the time.

His family and many of his compatriots consider him a national hero even today.

PRINCIP DESCENDENT OF GAVRILO PRINCIP "I'm proud of him, and his action, because he was a man who loved his nation. It is well known how the villagers lived in Bosnia back then, particularly in the mountainous areas, where they didn't even have enough food. He sought revenge for them. At the 1918 peace conference in Washington, everybody agreed that the war was actually caused by Austria and Germany, and not little Serbia."

Gavrilo Princip died in prison at the age of 23, just a few months before World War One ended in 1918.

Aljosa Milenkovic, CGTN, Sarajevo.