The Battle of Kniggrtz (or Sadowa) was the decisive battle of the Austro-Prussian War in which the Kingdom of Prussia defeated the Austrian Empire. It took place on 3 July 1866, near the Bohemian towns of Kniggrtz, (now Hradec Krlov, Czech Republic) and Sadowa (now Sadov, Czech Republic).

Prussian forces, totaling around 285,000 troops, used their superior training and tactical doctrine and the Dreyse needle gun to win the battle and the entire war at Kniggrtz on their own. Prussian artillery was ineffective and almost all of the fighting on the Prussian side was done by the First Army under Prince Friedrich Karl and one division from the Second Army. The Prussian 7th Infantry Division and 1st Guards Infantry Division attacked and destroyed 38 out of 49 infantry battalions of four Austrian corps at the Swiepwald and Chlum at the center of the battlefield, deciding the outcome of the struggle and forcing an Austrian retreat at 15:00, before any Prussian reinforcements could even seriously engage the Austrian flanks.

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.