In the Franco-Prussian War of 1870 he was not given a command in the field, but after the opening disasters had shaken the Ollivier ministry he was entrusted by the empress-regent with the portfolio of war, and became president of the council (10 August). He at once, with great success, reorganized the military resources of the nation. He claimed to have raised Marshal MacMahon's force at Châlons to 140,000 men, to have created three new army corps, 33 new regiments and 100,000 gardes mobiles, and to have brought the defences of the capital to a state of efficiency – all this in 24 days.