Mangin became a member of the Supreme War Council and inspector general of French colonial troops. He fell seriously ill at his Paris home on 9 March 1925. Suffering from pain, he became incoherent and partly paralysed. The following day he was diagnosed as suffering from appendicitis and as having suffered a stroke, though it was rumoured he may have been poisoned. He died two days later, on 12 March. His remains were interred in Les Invalides in 1932, and a bronze statue by Maxime Real del Sarte erected in his honour in 1928 in the Place Denys-Cochin, Paris.