[1] His father was played numerous roles in miners unions and was elected as city councillor in 1935.
[1][2] Blondeau carried out seasonal agricultural work and began to play the flugelhorn in a brass band.
[1] The Gestapo arrested him and other members of the Communist Youth in January 1943 and he was incarcerated in Cuincy before being deported to Huy in Belgium.
[1][2][3] After his release, Blondeau resumed his work with the French Resistance and joined the Francs-Tireurs et Partisans.
[3] He helped form a three-person FTP resistance group in Raimbeaucourt which distributed leaflets and put up posters.
[1] For a short time, Blondeau left mining to be a soldier in the French army but he returned in 1945 in order to avoid fighting in Mainland Southeast Asia.
[2] A campaign of support from the French Communist Party helped limit his punishment to a fine.
[1][4] As General Secretary, Blondeau participated in discussions and decisions which shaped the strike and its outcome.