German Empire

The German Empire or the Imperial State of Germany, also referred to as Imperial Germany, the Second Reich, the Kaiserreich, as well as simply Germany, was the period of the German Reich from the unification of Germany in 1871 until the November Revolution in 1918, when the German Reich changed its form of government from a monarchy to a republic.
It was founded on 18 January 1871 when the south German states, except for Austria, joined the North German Confederation, and the new constitution came into force, changing the name of the federal state to the German Empire and introducing the title of German Emperor for Wilhelm I, King of Prussia from the House of Hohenzollern. Berlin remained its capital, and Bismarck, Minister-President of Prussia, became Chancellor, the head of government. As these events occurred, the Prussian-led North German Confederation and its southern German allies were still engaged in the Franco-Prussian War.

Wikipedia