With the outbreak of the First World War, Fayolle was recalled from retirement by the French Commander-in-Chief Joseph Joffre and given command of the 70th Infantry Division. Fayolle took part in the fighting near Nancy, notably the Battle of Grand Couronné, which helped make possible the French victory at the First Battle of the Marne. Later, Philippe Pétain took command of the Corps in which Fayolle was serving, and the two commanders became close.