Editing Unification of Germany (section)

====Background====
{{Main|Causes of the Franco-Prussian War}} 
By 1870 three of the important lessons of the Austro-Prussian war had become apparent. The first lesson was that, through force of arms, a powerful state could challenge the old alliances and spheres of influence established in 1815. Second, through diplomatic maneuvering, a skilful leader could create an environment in which a rival state would declare war first, thus forcing states allied with the "victim" of external aggression to come to the leader's aid. Finally, as Prussian military capacity far exceeded that of Austria, Prussia was clearly the only state within the Confederation (or among the German states generally) capable of protecting all of them from potential interference or aggression. In 1866, most mid-sized German states had opposed Prussia, but by 1870 these states had been coerced and coaxed into mutually protective alliances with Prussia. If a European state declared war on one of their members, then they all would come to the defense of the attacked state. With skilful manipulation of European politics, Bismarck created a situation in which France would play the role of aggressor in German affairs, while Prussia would play that of the protector of German rights and liberties.{{Sfn|Howard|1968|pp=4–60}}

At the Congress of Vienna in 1815, Metternich and his conservative allies had reestablished the Spanish monarchy under [[Ferdinand VII of Spain|King Ferdinand VII]]. Over the following forty years, the great powers supported the Spanish monarchy, but events in 1868 would further test the old system, finally providing the external trigger needed by Bismarck.{{Citation needed|date=December 2024}}