Which state pursued the policy of uniting Germany in the 60s of the 19th century?

The unification of Germany into a politically and administratively united nation-state officially took place on January 18, 1871 in the Hall of Mirrors at the Palace of Versailles in France. The princes of the German states, with the exception of Austria, gathered there to proclaim William I King of Prussia Emperor of Germany after the French surrender in the Franco-Prussian War.
The model of diplomatic spheres of influence that emerged from the Congress of Vienna in 1814-15 after the Napoleonic Wars confirmed Austrian dominance in Central Europe. The participants in the Vienna talks did not take into account the growing power of Prussia within and among the German states and therefore could not foresee that Prussia would rise to challenge Austria for the leadership of the German peoples.
Answer: Prussia.

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