As a Romanian jew, he was first a victim of the xenophobic policies of the medical profession of the 1930s and 1940s, and later, of the antisemitic laws implemented by the Vichy regime.

As a result, in February 1941, he was prohibited from continuing his work and compelled to close his practice.

However, he chose to remain in the village and was provided lodging at the café-hotel at la Gare (2, place de la Gare), where, despite being banned from practicing, he persisted in providing medical care to patients. 

The 16th and 30th April, 1942 two trains on the Paris-Cherbourg line, near the Moult-Argences station, were derailed by the French resistance. In retaliation the German occupying authorities chose a hundred people from a list of communists and jews to be apprehended and held hostages. The doctor was arrested in his home the 2nd of May 1942. Imprisoned in Falaise and then released, he was apprehended a second time during the night of the 7th to 8th May 1942 and taken to the Petit-Lycée in Caen, where his name is written on a memorial plaque.

From there, he was first brought to a camp in Compiègne-Royallieu and on the 6th of July 1942, he was deported in the ‘45.000’ convoy train to Auschwitz, where he was registered under the number 46280.

Doctor Marc Grunberg died at the age of 36 on August 12th 1942, officially from illness but more likely murdered in a gas chamber.