Her father was a tailor and the first fifer for a Lorraine Regiment but who yearned for a life of showbiz and eventually lived his dream in a small theatre in Bayeaux, he conducting the orchestra, his wife playing the soubrette roles. When their daughter was old enough, she too wound up on the boards.
It was a provincial affair, but shuffled along well enough. Then, in one of those dramatic turns best suited for bad movies, Mademoiselle Raucourt, célèbre tragédienne happened to be passing through, saw the troupe and more to the point, saw something special in the now fourteen year old Marguerite. She whisked the young thing off the Paris and and put her through the paces, which eventually meant entree to the Comedie Francais. Her first major role was as Clytemnestra in Iphigenia in Aulis. (She sounds a bit young for the role, but what is acting if not a convincing lie?)