How did Gavrilo Princip start world war 1?

noo he didnt he just farted His shooting the Archduke was used as an excuse, certainly. But it is then a great stride to sinking the Lusitania, the Russian Revolution or Tannenburg, or the horrors of Verdun, the Somme, Ypres and so on. Truth is certainly the first casualty of war. It would be a very severe indictment to lay upon the actions of one man. The struggle for European power had been fomenting for many years. Quite what all this has to do with what Princip was objecting to is also vague and conditioned by opinion, far removed from his action & responsibility. My answer directly to the question is therefore No. Which is all I want to have in common with the first answer !