Which country was the first to defeat Napoleon—Spain, England, Austria, or Italy?

The first country to deal a significant defeat to Napoleon was England. The English naval victory at the Battle of Trafalgar in 1805 was a major defeat for Napoleon, although it was not on land. The battle was fought between the British Royal Navy, under Admiral Lord Nelson, and the combined fleets of the French and Spanish Navies. Trafalgar ended Napoleon's plans to invade England and established British naval supremacy.

However, if you were specifically asking about a land battle, it is a bit more complex as Napoleon was defeated in several battles by different coalitions. For instance, the Battle of Leipzig in 1813, also known as the Battle of the Nations, was another significant defeat for Napoleon, where the forces of Austria, Prussia, Russia, and Sweden prevailed against the French Army.

Napoleon Bonaparte was a French military leader and emperor who rose to prominence during the French Revolution and its associated wars. He was known for his military strategies and the Napoleonic Wars which involved complex alliances and multiple coalitions. Despite his early victories which saw him conquer a large part of Europe, Napoleon faced opposition from a range of other European powers, most prominently the United Kingdom, Prussia, Russia, and Austria. These countries were at various times part of different coalitions that eventually defeated Napoleon. His final defeat came at the Battle of Waterloo in 1815, at the hands of the Duke of Wellington's Anglo-Allied army and a Prussian army under the command of Gebhard Leberecht von Blücher. After this defeat, Napoleon was exiled to the island of Saint Helena, where he spent the rest of his life. Napoleon's impact on Europe was profound, and his legal reforms, particularly the Napoleonic Code, have had a lasting influence on the civil law jurisdictions of many countries throughout the world.