De Froment enrolled at Saint-Cyr and, after a standard beginning to his career, in 1939 he was sent on as special mission to Poland, where he was present for the debacle.
Along with Frenay, Robert Guédon and Jacques-Yves Mulliez, Froment was involved in the creation of the newspaper Les Petites Ailes de France, which was first circulated on 17 May 1941.
Towards the beginning of February 1942, Combat Zone Nord, the group led by Guédon and to which de Froment was attached, was scourged by a wave of arrests.
Greatly isolated, de Froment nonetheless continued to expand his network in industrial and railway circles across the whole of the zone occupée.
Terribly weakened, de Froment reached France and recuperated in the sanatorium at Briançon where, in 1946, he transcribed the history of his deportation to Mauthausen.