The War of the Third Coalition was a European conflict spanning the years 1803 to 1806. During the war, France and its client states under Napoleon I, defeated an alliance, the Third Coalition, made up of the United Kingdom, the Holy Roman Empire, the Russian Empire, Naples, Sicily and Sweden. Prussia remained neutral during the war. In what is widely regarded as the greatest victory achieved by Napoleon, the Grande Armée of France defeated a larger Russian and Austrian army led by Emperor Alexander I and Holy Roman Emperor Francis II at the Battle of Austerlitz.