== The incident == 

 "The edited telegram was to be presented henceforth as the cause of the war."  By whom?  The French declared war.  The Prussians via Bismark may have hoped to provoke it.  The line infers that the Prussians used the telegram as a cause for war.  They did not declare it and there doesn't appear to be evidence of what they would have done if the French had not taken the bait.