Born on February 7, 1920, in Cardiff-Edmonton (Alberta), from French parents who had migrated to Canada, Louis arrives in France in 1926. He attends school, becomes a professor at the petit séminaire of Annonay and is ordained a priest on December 19, 1942.
On July 8, 1943, he is required by the Service du Travail Obligatoire created by the Government of Vichy and sent to Germany. He is assigned to a chemical factory, in I.G. Bitterfeld, near Leipzig. During this time he celebrates mass for French workers, directs the Action Catholique in the region together with Roger Martins, a jociste from Roubaix-Tourcoing, and he prepares people to receive Catholic Sacraments: Baptism and First Communion. He is able to celebrate mass every day, first in the parish church, in French – as long as he was allowed to – and then, when it became forbidden, he celebrated mass in the private chapel of the sisters of Bitterfeld.
As a result of the Nazi decree of December 3, 1943, against the French Action Catholique amongst the French workers living in Nazi Germany, he is arrested on September 19, 1944, after a mass celebrated in the woods. Together with him other 40 young workers and activists and priests of Gau Halle-Merseburg are arrested.
Father Doumain is interrogated first in Bitterfeld then in Halle. The Gestapo offers to free him if he promises not to celebrate mass anymore. Father Doumain refuses their proposal and therefore, on November 21 1944, he is sent off to the disciplinary camps of Spergau and Zoschen, created to eliminate prisoners.
He dies at Zoschen, on December 20, after undergoing throat surgery. He was 24 years old.
He is part of the fifty French victims of Nazi persecution, the so-called “Martyrs de l’Apostolat”. Their beatification case was open in 1988.