The Emperor's Collar
On the day of the assassination attempt, Libényi stalked the Emperor as he was taking a walk with one of his officers. As Franz Josef paused to look over a railing, Libényi saw his chance and sprung into action. He ran up behind the Emperor and jabbed a knife in his neck. The Emperor always wore a uniform and its stiff collar protected him from the full force of the weapon.
The officer accompanying the Emperor struck back at the assassin with his sabre. A local butcher jumped in and tackled Libényi. The Emperor had a bloody gash in his neck, but he survived.
That appears to have been the last of Franz Josef's good luck. His brother Ferdinand Maximilian Joseph would be shot by a firing squad after an unsuccessful rule as the Emperor of Mexico. His only son and heir to the throne, Archduke Rudolf, committed suicide. Another brother, Karl Ludwig, died after drinking some bad water while on a pilgrimage through the holy land. His queen was stabbed to death by an Italian anarchist.
With all this carnage, the heir to the throne was now the Emperor's nephew, Franz Ferdinand. He was driving through Sarajevo with his wife when a Serbian nationalist shot and killed them both. The murders set off a shockwave across Europe, and served as the catalyst for the first World War.
Some scholars have pondered what course history would have taken had the Emperor's collar been a little less stiff.