Commanded the XX Corps at Nancy at the outbreak of war, after being promoted to general of brigade (1907) subsequent to his appointment of Director at the Ecole Superieure de la Guerre, where he was instrumental in the training of the French officer corps in the importance of firepower and security and the role of will and elan. Driven back by Crown Prince Rupprecht's Sixth Army at Morgange, he was given command of the 'Foch Detachment' of three corps between the Fourth and Fifth Armies. Joffre's deputy in the north during the 'Race to the Sea' (October-November 1914), directed the first battle of Ypres, directed French forces at the Somme. Succeeded General Petain as Chief of the French General Staff (11 May 1917). Made Allied generalissimo in the west on the recommendation of General Haig. Promoted to Marshal on 6 August 1918, he dictated armistice terms to the Germans and was appointed president of the Allied military committee at Versailles.