Die Emser Depesche
Today is the anniversary of the Emser Depesche incident, which led sofort to the Franco-Prussian War. The blame attached to Bismarck by most historians seems a little overdone to me, in line with general prussiabashing, but I'm no expert. If indeed the Prussians did provoke France into war it was a lesson well learnt by France/England/Russia in 1914, some would say.
Some more reading: