World War 1 was a global conflict that lasted from 1914 to 1918. Two of the most significant battlefields of this war were the Battle of Mons and the Battle of Ypres. The Battle of Mons was fought in August 1914 and was the first major battle of the war. It was fought between the British Expeditionary Force and the German Army, with the British ultimately retreating. The Battle of Ypres was fought in April 1915 and was one of the longest and bloodiest battles of the war. It was fought between the Allied forces and the German Empire, with the Allies eventually emerging victorious.