Full of his schemes for the aggrandisement of Prussia at the expense of Austria, he stirred up and worked this quarrel for all it was worth, the upshot being the Prusso-Austrian War (the so-called Seven Weeks' War) of the summer of 1866.

The war was brought about by the arbitrary dissolution of the German Confederation--i.e.the Federal Assembly--in which, owing to the alarm created by Prussian insolence and aggression, Austria had the backing of the majority of the States.
This step was followed by Bismarck's dispatching an ultimatum to Hanover, Saxony, and Hesse Cassel respectively, all of which had voted against Prussia in the Federal Assembly, followed, on its non-acceptance, by the dispatch of Prussian troops to occupy the States in question.

Hard on this act of brutal violence came the declaration of war with Austria.
At Koeniggratz the Prussian army was victorious over the Austrians, and henceforth the hegemony of Central Europe was decided in favour of Prussia.

Austria, under the Treaty of Prague (August 20, 1866), was completely excluded from the new organization of German States, in which Prussia--i.e.Bismarck--was to have a free hand.

The result was the foundation of the North German Confederation, under the leadership of Prussia.