How did the Franco-Prussian War encourage southern German states to join Prussia?

The Franco-Prussian War served as a powerful catalyst for German unification by overcoming the political resistance, or "particularism," that had previously kept the southern German states—Bavaria, Württemberg, and Baden—separate from the North German Confederation.12

Prior to the conflict, public opinion in the south remained deeply distrustful of Prussian dominance. Otto von Bismarck recognized that political integration could not be achieved through reason alone; he believed that only a common patriotic struggle against foreign aggression could unite the nation. By manipulating the Ems telegram to provoke France into declaring war, Bismarck successfully framed the conflict as a defensive necessity against French aggression.132

This perceived threat galvanized the southern states, which honored their treaty obligations and placed their military forces under the command of the Prussian king, William I. The subsequent "brotherhood of arms" and the shared intoxication of victory over France effectively dismantled the remaining barriers to unity, leading the southern states to join the North German Confederation and form the German Empire in 1871.413