Prussian aggression in Luxemburg produced a crisis with France in 1867, though the growing tension between Prussia and France was tided over on this occasion.

But Bismarck only bided his time.
The occasion was furnished him by the question of the succession to the Spanish throne, in July 1870.

By means of a falsified telegram Bismarck precipitated war, in which Prussia was joined by all the States of Germany.

The subsequent course of events is matter of recent history.

The establishment of the new Prusso-German empire by the crowning of Wilhelm I at Versailles, with the empire made hereditary in the Hohenzollern family, completed the work of Bismarck and the setting of the Prussian jack-boot on the necks of the German peoples.
The Prussian military and bureaucratic systems were now extended to all Germany--in other words, the rest of the German peoples were made virtually the vassals and slaves of the Prussian monarch.