Cause:
For some years previously there had been increasing friction between France and Prussia, owing chiefly to Louis Napoleon’s apprehensions as to the possibility of closer union between Prussia and the South German states, his repeated endeavours to extend the Eastern frontier of France, and Bismarck’s counter-moves to frustrate his designs. The desire also for a united Germany was growing stronger, and Bismarck believed it could not be completed without a conflict with France.