This style of writing almost seems deliberatly chosen to lose the reader. By the time you're done, you barely remember what the subject is.
It's hard to understand because it could easily be four or more sentences.
Franz Ferdinand would have gone from Sarajevo untouched had it not been for the actions of his staff. His staff made number of mistakes so that Ferdinand was an easy target to Princip. [who by blunder after blunder contrived that his car should be slowed down and that he should be presented as a stationary target in front of Princip]. Princip was the one conspirator who was really a danger. [of real and mature deliberation]. He (that is, Princip) had finished his cup of coffee and was walking back through the streets and was aghast at the failure of himself and his friends. That failure would expose the country to terrible punishment without having inflicted any loss on authority.