The battle that marked the beginning of the end for Napoleon at the hands of the Seventh Coalition was the Battle of Leipzig, also known as the Battle of Nations, fought in October 1813. This pivotal battle pitted Napoleon's French forces against a coalition of Russia, Prussia, Austria, and Sweden. It resulted in a decisive defeat for the French and was one of the largest battles in European history at that time. The loss significantly weakened Napoleon's army and diminished his control over Europe. Following this defeat, he faced further military setbacks, leading to his eventual abdication and exile in 1814.