Second of nine children. Lifelong layman in the diocese of Rennes, France. Joined the Boy Scouts at age 10, and considered himself a Scout the rest of his life. Member of the Young Christian Workers (Jocists). Following the Nazi invasion of France, Marcel and some friends would go each day to the train station to assist refugees arriving from the east. Engaged to Marguerite Derniaux, but due to the war they never married. Conscripted into a forced labour camp in Thuringia, Marcel tried to use his time to minister to others enslaved by the Nazis. Arrested by the Gestapo on 19 April 1944 for membership in the Jocists, which was considered an outlawed secret society; the arresting officers said Marcel was being taken because he was “too much of a Catholic”. Sent to camps in Gotha, then Flossenburg and finally the Güsen I and II parts of the Mauthausen, Austria camp where he did forced labour most of the day, was abused the rest, and finally died as a result of the miserable conditions. Martyr.
- 19 March 1945 in Mauthausen, Upper Austria, Austria of tuberculosis and dysentery
- buried in a mass grave outside the walls of the camp
- “Blessed Marcel Callo“. CatholicSaints.Info. 26 August 2016. Web. 1 October 2016. <>