The Battle of the Somme, also known as the Somme Offensive, was one of the bloodiest and longest battles of World War I. It lasted from July 1 to November 18, 1916, and resulted in more than 1 million casualties on both sides. The battle was fought between the forces of the British and French Empires against the German Empire in the Somme River valley in northern France. The battle was a major victory for the Allies, as it helped to break the German lines and eventually lead to the end of the war.