6. Alsos was enlarged for deployment in France
On April 4, 1944, US Secretary of War Henry L. Stimson created a new, considerably larger Alsos mission for deployment to France. Colonel Pash assumed command of the new mission, which reported through G 2 and G 3 to General Groves. Following the invasion in June, American, British, Canadian, and Free French forces remained bottled up in Normandy for several weeks. The Alsos mission spent its time analyzing the same data as had its predecessor. It also worked with British and French agents to identify key scientists in occupied France with likely knowledge of the German atomic weapons program. At this point, several key British officers and scientists lobbied their government to create a separate British program. In part, the British expressed concern over the American-led program’s failure to produce any hard, accurate information regarding the German pursuit of atomic weapons.
The British concern came from the very real peril their homeland came under from the German V-weapons. Great Britain had borne the burden of German aerial attacks for nearly five years. A German radioactive device delivered by a V-2 rocket on a British city presented a terrifying situation. The British considered developing their own missions for several weeks before agreeing to continue to work within the Alsos missions, under the command of Colonel Pash. When a breakout finally occurred in Normandy, supported by a second invasion in the South of France, Alsos teams moved to the continent. Their first mission in France included the location of scientists with experience in the necessary fields to build nuclear reactors and created atomic weapons. Near the top of their list appeared the eminent French physicist, Frederic Joliot-Curie.