What did the United States Army use during Operation Peppermint to prevent the Germans from  disrupting the 1944 Normandy Landings?
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. Normandy landings: The Normandy landings (codenamed Operation Neptune) were the landing operations on Tuesday, 6 June 1944 (termed D-Day) of the Allied invasion of Normandy in Operation Overlord during World War II.
radioactive poisons