The Battle of Nations was a major conflict fought in 1813 near Leipzig, Germany. It was the largest battle of the Napoleonic Wars and involved over 600, 000 soldiers from various European nations. The French army, led by Napoleon, was defeated by a coalition of Russian, Prussian, Austrian, and Swedish forces. This battle marked the end of Napoleon's rule in Europe and is considered one of the most important battles in European history. The term WAR is an appropriate three-letter solution for this crossword puzzle.