Respectfully Quoted: A Dictionary of Quotations. 1989.
Emilio Mola (18871937)
EMILIO MOLA. A term used by General Mola during the siege of Madrid in 1936, referring to the contingent of supporters within the city who would aid the armys four columns attacking from outside.
A fully documented account of the term, its spread, its popularity, and its change of meaning may be found in Dwight L. Bolinger, Fifth Column Marches On, American Speech, February 1944, pp. 4749. The first use in English, in a report from Spain, appears in The New York Times, October 17, 1936, p. 9, col. 4.