Bloch and her family, Jews, evaded capture by the Germans in Paris after its occupation by Nazi Germany in summer 1940.

In May 1942, she made a dangerous crossing of the Pyrenees into Spain and hence to SOE headquarters in London to present Starr's request for more aid to his resistance forces.

Her mother, her brother Jean-Claude, and Denise then lived a clandestine life avoiding persecution as Jews by using false papers and identities.

In the summer of 1942, the family was smuggled across the border from occupied to unoccupied Vichy France arriving in Lyon on 17 July.

[1] In Lyon Bloch became a secretary for Jean-Maxime Aron, a Jewish engineer for Citroen who was working with the French Resistance and the SOE network led by Philippe de Vomécourt.

Realizing she was in danger, on 26 October SOE agent Paul Sarrette decided that he would accompany her from Lyon to a safe house in Marseilles.

She dyed her black hair blond as a disguise, but her height of 5 feet 10 inches (178 cm) made her conspicuous.

In January 1943, Sarrette accompanied Bloch to Toulouse which was the territory of SOE agents George Reginald Starr and Henri Sevenet.

She walked across the Pyrenees mountains with Maurice Dupont as a guide, but the Spanish briefly arrested her and confiscated Starr's report.

[7] Illustrating that the Germans knew of Bloch, on 29 June 1943 she was convicted in absentia and sentenced to ten years hard labor.

Working in the Nantes area for the Clergyman circuit,[10] the pair re-established contact with SOE agent and Benoist's fellow racing car driver, Jean-Pierre Wimille.

Their objectives were to destroy pylons on the power line at Ile Heron in Nantes and to interrupt railroad transportation in support of the allied invasion of France which took place on 6 June.

Along with SOE agents Violette Szabo and Lilian Rolfe she volunteered for a work party at Torgau in Saxony, where conditions were better than at Ravensbrūck.

Camp commandant Fritz Suhren read the order for their execution and they were each shot in the back of the head with a small caliber pistol.