The Battle of the Marne, which took place in 1914, was a major battle of World War I fought between the German and French armies. The Battle of Argonne was fought in 1918 and was the longest battle of the war, lasting 47 days. The Battle of Verdun, which began in 1916, was one of the bloodiest battles of the war and lasted for over 300 days. All three battles were fought on the Western Front and were major sites of World War I.