The Peace of Prague (German: Prager Frieden) was a peace treaty signed by the Kingdom of Prussia and the Austrian Empire at Prague on 23 August 1866. In combination with the treaties of Prussia and several south - and central German states it effectively ended the Austro-Prussian War.The treaty was lenient toward the Austrian Empire because Otto von Bismarck had persuaded Wilhelm I that maintaining Austria's place in Europe would be better in the future for Prussia than harsh terms, as Bismarck realized that without Austria, Prussia would be weakened in a relatively hostile Europe. At first, Wilhelm I had wanted to push on to Vienna and annex Austria but Bismarck stopped him, even threatening to resign, and, more drastically, to hurl himself out of the fourth story window of Nikolsburg Castle. Indeed, it was this relative cordiality with Austria that caused the clamouring factions of Europe in 1914 that led to the Great War.

Austria lost Veneto, ceded to Napoleon III of France in the Treaty of Vienna, who in turn ceded it to Italy. Austria refused to give Venetia directly to Italy because the Austrians believed to have crushed the Italians during the war. The Habsburgs were permanently excluded from German affairs (Kleindeutschland). The Kingdom of Prussia thus established itself as the only major power among the German states. The German Confederation was abolished. The North German Confederation had been formed as a military alliance five days prior to the Peace of Prague, with the north German states joining together; the Southern German states outside of the Confederation were required to pay large indemnities to Prussia.

The Austro-Prussian War, Seven Weeks' War, German Civil War, Brothers War or Fraternal War, known in Germany as Deutscher Krieg ("German War"), Deutscher Bruderkrieg ("German war of brothers") and by a variety of other names, was fought in 1866 between the Austrian Empire and the Kingdom of Prussia, with each also being aided by various allies within the German Confederation. Prussia had also allied with the Kingdom of Italy, linking this conflict to the Third Independence War of Italian unification. The Austro-Prussian War was part of the wider rivalry between Austria and Prussia, and resulted in Prussian dominance over the German states.

The major result of the war was a shift in power among the German states away from Austrian and towards Prussian hegemony. It resulted in the abolition of the German Confederation and its partial replacement by the unification of all of the northern German states in the North German Confederation that excluded Austria and the other Southern German states, a Kleindeutsches Reich. The war also resulted in the Italian annexation of the Austrian province of Venetia.