The Battle of the Somme, also known as the Somme Offensive, was a battle of the First World War fought by the armies of the British and French empires against the German Empire. It took place between 1 July and 18 November 1916 on either side of the River Somme in France. The battle was one of the largest of World War I, in which more than 1,000,000 men were wounded or killed, making it one of humanity's bloodiest battles. A Franco-British commitment to an offensive on the Somme had been made during Allied discussions at Chantilly, Oise in December 1915. The Allies agreed upon a strategy of combined offensives against the Central Powers in 1916, by the French, Russian, British and Italian armies, with the Somme offensive as the Franco-British contribution. The main part of the offensive was to be made by the French Army, supported on the northern flank by the Fourth Army of the British Expeditionary Force. When the German Army began the Battle of Verdun on the Meuse in February 1916, many French divisions intended for the Somme were diverted and the supporting attack by the British became the principal effort. The First day on the Somme was a serious defeat for the German Second Army, which was forced out of its first line of defence by the French Sixth Army, from Foucaucourt-en-Santerre south of the Somme to Maricourt on the north bank and by the British Fourth Army from Maricourt to the vicinity of the Albert–Bapaume road. 1 July 1916 was also the worst day in the history of British Army, which had c. 60,000 casualties, mainly on the front between the Albert–Bapaume road and Gommecourt, where the attack failed disastrously, few British troops reaching the German front line. The British Army on the Somme was a mixture of the remains of the pre-war regular army, Territorial Force and the Kitchener Army which was composed of Pals battalions, recruited from the same places and occupations, whose losses had a profound social impact in Britain.