She travelled in several countries, and had long stays in Poland, where she lived with her sister and her brother-in-law, Adam Rosé, a diplomat and minister.
Its subject was the life and work of David Ferdinand Koreff, a German doctor whose connections included some notable French writers.
[3] Suffering from lung disease, Marietta Martin spent several years between 1927 and 1931 in Switzerland, in a sanatorium in Leysin in the Canton of Vaud.
In 1936, Martin was approached by Maurice Tailliandier (1873-1951), out-going deputy of the second electorate of Pas-de-Calais (Arras), where he belonged to the Republicain et social group.
Others who worked in this movement included Henri and Annie de Montfort, Paul Petit, Émile Coornaert, Suzanne Feingold and Raymond Burgard.
Marietta Martin was accused of writing and circulating clandestine publications and of being an activist in the Libération Nationale movement of Henri Frenay and Robert Guédon.
She was imprisoned in La Santé Prison in Paris, and then deported to Germany 16 March 1942, where she stayed in eight successive penitentiary establishments.
Along with Paul Petit and Raymond Burgard, she was condemned to death on 16 October 1943 by the People's Court (Germany) (Volksgerichtshof) of Saarbrücken for complicity with the enemy.
Other Resistance workers in the prison at that time included Elizabeth Dussauze, Jane Sivadon, Hélène Vautrin and Odile Kienlen.