Bismarck engineers another war in 1870, this time against France.

The conflict will become known to history as the Franco-Prussian War.

Nationalistic fervor is ignited by the promised annexation of Lorraine and Alsace, which had belonged to the Holy Roman Empire and had been seized by France in the seventeenth century.

With this goal in sight, the south German states eagerly join in the war against the country that has come to be seen as Germany's traditional enemy.

Bismarck's major war aim—the voluntary entry of the south German states into a constitutional German nation-state—occurs during the patriotic frenzy generated by stunning military victories against French forces in the fall of 1870.

Months before a peace treaty is signed with France in May 1871, a united Germany is established as the German Empire, and the Prussian king, Wilhelm I, is crowned its emperor in the Hall of Mirrors at Versailles.