World War I, then known as The Great War, was started when Gavrilo Princip assassinated Austrian Archduke Franz Ferdinand. In 1914, Ferdinand was travelling through the streets of Sarajevo, which was then part of Austria-Hungary (now Bosnia and Herzegovina).
A group called The Black Hand staged an assassination attempt that went poorly. A grenade was thrown under Ferdinand’s car, but it failed to detonate in proper timing and instead injured the car behind his. The assassins all fled, and the people injured in the car were taken to a hospital.
Franz Ferdinand wanted to visit the people in the hospital, but his driver got lost trying to find out where it was. Eventually, they decided to stop at a cafe. At that cafe eating a sandwich was, coincidentally, Gavrilo Princip, one of the assassins from earlier. He grabbed his pistol and shot Franz Ferdinand.
It stands to reason that if the driver had not gotten lost, and Princip had not stopped for a sandwich, Ferdinand might not have been assassinated, and World War I could have been avoided. What’s interesting is what would have happened if Ferdinand hadn’t been assassinated, or, as mentioned previously, if Annie Oakley had accidentally shot Kaiser Wilhelm II.
If World War I had been avoided, then there wouldn’t have been harsh reparations and a struggling economy for Germany, which means Hitler wouldn’t have been elected or risen to power, meaning World War II could also have been avoided. If World War II had been avoided, the Cold War, Korean War, and Vietnam Conflict may also have been avoided.