Operation Peppermint Operation Peppermint was the codename given during World War II to preparations by the Manhattan Project and the European Theater of Operations United States Army ( ETOUSA ) to counter the danger that the Germans might disrupt the June 1944 Normandy landings with radioactive poisons . In response , the Metallurgical Laboratory in Chicago and the Victoreen Instrument Company in Cleveland developed portable radiation detection devices suitable for use in the field . In 1944 , Major General Leslie R . Groves , Jr . , director of the Manhattan Project , sent Major Arthur V . Peterson to brief General Dwight D . Eisenhower and his senior staff officers at the Supreme Headquarters Allied Expeditionary Force ( SHAEF ) . In response , ETOUSA initiated Operation Peppermint . Special equipment was prepared . Eleven survey meters and a Geiger counter were shipped to England in early 1944 , along with 1 , 500 film packets , which were used to measure radiation exposure . Another 25 survey meters , 5 Geiger counters and 1 , 500 film packets were held in storage in the United States , but in readiness to be shipped by air with the highest priority . Chemical Warfare Service teams were trained in its use , and Signal Corps personnel in its maintenance . The equipment was held in readiness , but the preparations were not needed , because the Germans had not developed such weapons . Background . When the Manhattan Project assumed responsibility for the development of nuclear weapons in September 1942 , it also assumed responsibility for the development of suitable countermeasures . At the time , the threat posed by the German nuclear energy project was taken very seriously . Consideration was given to issuing a public warning of the danger of a German nuclear attack on the United States , but the director of the Manhattan Project , Brigadier General Leslie R . Groves , Jr . , considered the likelihood of this to be sufficiently remote that he rejected the notion of taking so drastic a step . A subcommittee of the S - 1 Uranium Committee , chaired by James B . Conant , and consisting of himself , Arthur Compton and Harold Urey , was appointed to look into the issue , and it similarly assessed the danger as low , but still sufficient to warrant taking some precautions . A program was initiated by the Metallurgical Laboratory in Chicago and the Victoreen Instrument Company in Cleveland to develop radiation detection devices suitable for use in the field . Some 48 portable detection meters were built in 1943 , half of which were capable of detecting 0 to 10 roentgen s per day , while the other half could detect from 0 to 100 roentgens per day . Instruments sets were stored at Manhattan District offices in Boston , Chicago , New York , San Francisco and Washington , D . C . , and the area engineer and some other officers were instructed in their use . A special team of scientists was created at the Metallurgical Laboratory who could respond to any reports of the use of nuclear weapons or radioactive poisons . It was considered more likely that Germany might employ such weapons against the United Kingdom , so four officers from the European Theater of Operations United States Army ( ETOUSA ) were summoned to Chicago where they were given a top secret briefing by the Manhattan District ' s Chicago area engineer , Major Arthur V . Peterson . They were told about possible forms such an attack might take , and what the effects and symptoms of them were , and they were given survey instruments and shown how to use them . They were enjoined to tell other officers in the theater to report unexplained fogging of film or illnesses with symptoms corresponding to the effects of radiation sickness . Preparations . As the date for the Normandy landings ( codenamed Operation Overlord ) drew near in early 1944 , Groves considered that risk was sufficient to send an officer to brief the Supreme Commander General Dwight D . Eisenhower of the possible use of radioactive poisons , particularly plutonium and fission products that might be created in their nuclear reactors . On 8 April 1944 , Peterson reported to the Supreme Headquarters Allied Expeditionary Force ( SHAEF ) and met with Eisenhower , his Chief of Staff , Lieutenant General Walter Bedell Smith , Assistant Chief of Staff ( G - 2 ) ( Intelligence ) , Major General John Whiteley , and his Assistant Chief of Staff ( G - 3 ) ( Operations ) , Major General Harold R . Bull . They considered creating an Allied plan to counter the danger , but Whiteley said that he would have to consult with the British command before this could be approved . Colonel G . S . Eyster from G - 3 was then ordered to prepare an American plan , under the codename Operation Peppermint . Further briefings were given to Admiral Harold Stark , and Lieutenant Generals Carl Spaatz and John C . H . Lee , and Eisenhower also wrote to Lieutenant General Hastings Ismay , the Chief of Staff of the Prime Minister of the United Kingdom , Winston Churchill to inform the British Chiefs of Staff , but no British or American commanders actually participating in Operation Overlord were informed . The British subsequently adopted a similar plan to Operation Peppermint , and SHAEF assumed responsibility for coordinating the British and American efforts . Scientific assistance was provided by the Cavendish Laboratory . Operation Peppermint provided for : Under Operation Peppermint , orders went out for medical personnel to report the details of any fogging or blackening of photographic or X - ray film , and medical officers were ordered to report diseases of unknown etiology involving fatigue , nausea , leukopenia or erythema . Eleven survey meters and a Geiger counter were shipped to England in early 1944 , along with 1 , 500 film packets , which were used to measure radiation exposure . Another 25 survey meters , 5 Geiger counters and 1 , 500 film packets were held in storage in the United States , but in readiness to be shipped by air with the highest priority . Peterson instructed Chemical Warfare Service personnel in the use of the equipment , and Signal Corps personnel in its maintenance . In the weeks leading up to D - Day , full - scale rehearsals of Operation Peppermint were carried out in order to test the plan and the equipment . Ground and aerial surveys were also carried out to detect the presence of radioactive substances in troop concentration areas , and at sites in the United Kingdom that had been bombed , but none were detected . Outcome . The Germans had not developed , and did not employ radioactive poisons , so Operation Peppermint was never put into effect . After VE - Day , the equipment and all the documents relating to Operation Peppermint were collected , returned to the United States , and handed over to the Manhattan Project . However , the effort put into developing portable radiation detection equipment was not wasted . Survey teams from the Manhattan Project used the equipment to assess the fallout from the Trinity nuclear test , the bombing of Hiroshima and Nagasaki , and Operation Crossroads , during which 10 , 000 film badges were used .