He belonged to the inter-war left, acting in René Clair's 1924 Dada film Entr'acte and editing Jean Renoir's 1931 On purge bébé.
Subsequently, he directed a number of films in the series "Une heure d'angoisse" based on the novels written by Marcel Allain for the Éditions Ferenczi.
It virulently denounces Freemasonry, parliamentarianism and Jews as part of Vichy's drive against them and seeks to prove a Jewish-Masonic plot.
[1] Mamy had also been a journalist on the collaborationist periodical L'Appel under Pierre Constantini (leader of the Ligue française d’épuration, d’entraide sociale et de collaboration européenne) and on the collaborationist journal Au pilori.
After being purged for collaboration with the enemy, he was condemned to death and executed at the fortress of Montrouge on 29 March 1949.