Fifth Column
Fifth column element
A fifth column is any group of people who undermine a larger group from within, usually in favor of an enemy group or nation. The activities of a fifth column can be overt or clandestine. Forces gathered in secret can mobilize openly to assist an external attack.
Second World War
By the late 1930s, as American involvement in the war in Europe became more likely, the term "fifth column" was commonly used to warn of potential sedition and disloyalty within the borders of the United States
A cardinal technique of the fifth column is the infiltration of sympathizers into the entire fabric of the nation under attack and, particularly, into positions of policy decision and national defense. From such key posts, fifth-column activists exploit the fears of a people by spreading rumours and misinformation, as well as by employing the more standard techniques of espionage and sabotage