After joining the Civil and Military Organization in 1942, he became its head in Aquitaine and, with the help of the British Special Operations Executive, he strongly developed his regional network, arming and training several thousand agents, and setting up an escape route and a radio link with London.
[2][3] When de Baissac was flown to Britain in August 1943, SCIENTIST's wireless operator Roger Landes took control of the network just as a Gestapo crackdown led to many arrests, including Grandclément's wife.
[4] Fearing for his wife's life, and suspicious of communist influence within the Maquis, the right-wing André Grandclément agreed to help the Germans, and the number of arrests increased and the SCIENTIST network began to collapse.
[1] It proved to be a costly error of judgement as two months later Grandclément's actions had crippled SCIENTIST, and led to the capture and execution of the circuit's arms instructor, Victor Hayes.
[6] In London he was suspected of being a double agent, but his name was cleared and he returned to Bordeaux in March 1944 as organiser of the ACTOR network, a new circuit tasked with making contact with surviving Resistance groups in the area and coordinating sabotage to support the D-Day landings.