Born in Souk Ahras, Algeria and of Corsican origins, Casanova studied law at university in Paris. He became secretary of the Communist cell there, and he entered the underground apparatus of the French Communist Party (PCF) in 1928, when he was just twenty-one years old. By 1936, he had become a close associate of Maurice Thorez, the party's secretary-general. Drafted into the French armed forces in 1939, Casanova was promptly taken prisoner; however, he escaped and resumed contact with the party through an intermediary, Claudine Chomat, in March 1942.
