In 1914, at the beginning of World War I, Magnard sent his wife and two daughters to a safe hiding place while he stayed behind to guard the estate of "Manoir de Fontaines" at Baron, Oise. When German soldiers trespassed on the property, Magnard fired at them, killing one soldier, and they fired back before setting the house on fire. It is believed that Magnard died in the fire, although his body could not be identified in the ruins. The fire destroyed all of Magnard's unpublished scores, including the orchestral score of his early opera "Yolande", the orchestral score of "Guercoeur" (the piano reduction had been published, and the orchestral score of the second act was extant), and a more recent song cycle.