In 1866, the feud between Austria and Prussia finally came to a head. There were several reasons behind this war. As German nationalism grew strongly inside the German Confederation and neither could decide on how Germany was going to be unified into a nation-state. The Austrians favoured the Greater Germany unification but were not willing to give up any of the non-German-speaking land inside of the Austrian Empire and take second place to Prussia. The Prussians however wanted to unify Germany as Little Germany primarily by the Kingdom of Prussia, whilst excluding Austria. In the final battle of the German war (Battle of Königgrätz) the Prussians successfully defeated the Austrians and succeeded in creating the North German Confederation.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): When did the strife between Austria and Prussia erupt?
1866