The French Ministry of Defence has a public database of soldiers who died on duty during the 1st World War. I just found the entry for this officer: http://www.memoiredeshommes.sga.defense.gouv.fr/en/ark:/4069... The most interesting part is the Images link (with an eye): it will show you a scan of the official death certificate from 1918. There are 1.3 millions soldiers in this database. 3 of them from my family.