 In October, French forces led by Fayolle advanced almost to Sailly Saillisol by successfully using the artillery-barrage system.On 31 December 1916, Fayolle was transferred to command the First Army.When Philippe Pétain was appointed Chief of the General Staff in April 1917, Fayolle was put in command of the Army Group Center, to the disappointment of Foch, who had hoped for the command himself; Pétain replaced Nivelle as Commander-in-Chief in May 1917.