Fortoul was often called to serve abroad in Japan and south-east Asia; between 1882 and 1885, he was in Tonkin in Indochina, returning home after being seriously injured.
Fortoul wurde oft zum Dienst in Japan und Südostasien abkommandiert; zwischen 1882 und 1885 war er in Tonkin in Indochina, von wo er schwer verwundet zurückkehrte.