Kammala jumla mai zuwa: Berthier ya ba da Grosbois ga 'yar'uwarsa kafin ya tafi soja da Yaƙin Duniya na 1 a ranar 1 ga Agusta 1914. A sojojin kyaftin da kuma shugaban wani kamfanin na chasseurs a lokacin
Yaƙin Aisne na uku, ya sami raunuka daga harbin harsashi a Fort de Condé-sur-Aisne kuma ya mutu daga gare su a ranar 30 ga Mayu, 1918. Ba shi da wata matsala. An binne shi a Château de Grosbois kamar mahaifinsa da kakansa.