Frédéric Joliot-Curie
The bunker was inspected on 10 September 1944 by the French atomic scientist Frédéric Joliot-Curie, accompanied by Sandys. Following the visit, Sandys ordered a Technical Inter-Services Mission under Colonel T.R.B. Sanders to investigate the sites at Mimoyecques, Siracourt, Watten, and Wizernes, collectively known to the Allies as the "Heavy Crossbow" sites. Sanders' report was submitted to the War Cabinet on 19 March 1945.