|1.||(originally) a group of Falangist sympathizers in Madrid during the Spanish Civil War who were prepared to join the four columns of insurgents marching on the city|
|2.||any group of hostile or subversive infiltrators; an enemy in one's midst|
People willing to cooperate with an aggressor against their own country. The term originated in a remark by Francisco Franco, the Spanish dictator, that he was marching on Madrid with four columns of troops, and that there was a “fifth column” of sympathizers within the city ready to help.
A secret subversive group that works against a country or organization from the inside, as in The right-to-life movement has established a fifth column among freedom-of-choice activists. This term was invented by General Emilio Mola during the Spanish Civil War in a radio broadcast on October 16, 1936, in which he said that he had una quinta columna ("a fifth column") of sympathizers for General Franco among the Republicans holding the city of Madrid, and it would join his four columns of troops when they attacked. The term was popularized by Ernest Hemingway and later extended to any traitorous insiders.
clandestine group or faction of subversive agents who attempt to undermine a nation's solidarity by any means at their disposal. The term is credited to Emilio Mola Vidal, a Nationalist general during the Spanish Civil War (1936-39). As four of his army columns moved on Madrid, the general referred to his militant supporters within the capital as his "fifth column," intent on undermining the loyalist government from within
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