Step 1: Understanding the Concept:
The Battle of Sedan was the decisive battle of the Franco-Prussian War. The question asks who was defeated in this battle.
Step 2: Detailed Explanation:
The Battle of Sedan was fought on September 1, 1870. The Prussian army, under the command of Helmuth von Moltke, decisively defeated the French army. The French Emperor Napoleon III himself was captured along with his entire army. This catastrophic defeat for France led to the fall of the Second French Empire and the proclamation of the Third Republic. For Prussia, this victory paved the way for the unification of Germany, which was proclaimed a few months later in the Palace of Versailles.
Step 3: Final Answer:
France was defeated in the Battle of Sedan.