Fifth column

Fifth column stands for any clandestine group of people which works inside a nation to undermine its strength (psychological warfare), while at the same time the nation suffers a direct attack from a foreign power.

The term was coined by General Mola in a radio address during the Spanish Civil War (1936-1939). As a Nationalist general, he sent four of his army columns to capture Madrid, which was being defended at the time by the Republican forces. The general referred to his hidden supporters inside the capital as his fifth column.

Originally, the term was used by Leon Trotsky as name for the Fifth Army, which was founded as an elite military unit during the Russian Civil War.

In the aftermath, Ernest Hemingway wrote his one and only play entitled The Fifth Column, which depicts the role of the two protagonists, a writer and a journalist, during wartime. The title hints at the similarity of the protagonists with the supporters of Emilio Mola, as both were performing "behind enemy lines" influence.