He headed the organisation in the insurance sector of the Confédération générale du travail (CGT), and he was also active in the Mouvement Jeunes Communistes de France (MJCF).
When arrested in Lyon on 15 March 1942, his knowledge of German as a native of Alsace allowed him to conceal his true identity from his interrogators, and he thus faced only minor charges.
On 24 May he escaped from prison with several colleagues and resumed his activities, organising sabotage in factories and opposing the drafting of French labour for the German war effort.
By 1944, the resistance had complex coordination structures including a military action committee (Comac) which directed the French Forces of the Interior (FFI).
[3] Maurice Kriegel-Valrimont, as he was now known, formally joined the French Communist Party (PCF) after the war and was elected to parliament in 1945 to represent an Alsace constituency.