Fifth column

A fifth column is any group of people who undermine a larger group—such as a nation or a besieged city—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. This term is also extended to organized actions by military personnel. Clandestine fifth column activities can involve acts of sabotage, disinformation, or espionage executed within defense lines by secret sympathizers with an external force.

Emilio Mola, a Nationalist general during the Spanish Civil War, told a journalist in 1936 that as his four columns of troops approached Madrid, a "fifth column" (Spanish: Quinta columna) of supporters inside the city would support him and undermine the Republican government from within. The term was then widely used in Spain. Ernest Hemingway used it as the title of his only play, which he wrote in Madrid while the city was being bombarded, and published in 1938 in his book The Fifth Column and the First Forty-Nine Stories.

Some writers, mindful of the origin of the phrase, use it only in reference to military operations rather than the broader and less well defined range of activities that sympathizers might engage in to support an anticipated attack.

In the United States at the end of the 1930s, as involvement in the European war seemed ever more likely, those who feared the possibility of betrayal from within used the newly coined term "fifth column" as a shorthand for sedition and disloyalty. The rapid fall of France in 1940 led many to blame a "fifth column" rather than German military superiority. Political factions in France blamed one another for the nation's defeat and military officials blamed the civilian leadership, all helping feed American anxieties. In June 1940, Life magazine ran a series of photos under the heading "Signs of Nazi Fifth Column Everywhere". In July 1940, Time magazine called fifth column talk a "national phenomenon". In August 1940 the New York Times mentioned "the first spasm of fear engendered by the success of fifth columns in less fortunate countries". One report identified participants in Nazi "fifth columns" as "partisans of authoritarian government everywhere", citing Poland,Czechoslovakia, Norway, and the Netherlands. Vidkun Quisling aided the Nazis during the campaign in Norway by proclaiming a Nazi government on the day of the German invasion in 1940, and his name of "quisling" is associated with Nazi collaborators.

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