A fifth column is a group of people who clandestinely undermine a larger group such as a nation from within, to help an external enemy.
The term originated with a 1936 radio address by Emilio Mola, a Nationalist General during the 1936–39 Spanish Civil War. As his army approached Madrid, a message was broadcast that the four columns of his forces outside the city would be supported by a "fifth column" of his supporters inside the city, intent on undermining the Republican government from within (see Siege of Madrid). The term was used as the title of Ernest Hemingway's only play, which he wrote while the city was being bombarded; the play was published in 1938 in his book The Fifth Column and the First Forty-Nine Stories.
In fact, this supposed "fifth column" did not prove very effective, as demonstrated by the fact that Madrid held out until 1939 despite very heavy fighting. Nevertheless, the term caught on and was used extensively, especially by those fighting the Fascists and Nazis.
The term was in wide use in Britain in the early stages of the Second World War where the fear of the fifth Column was used as justification for the mass internment, on the Isle of Man, of German nationals who resided in the United Kingdom. The United States and Canada interned U.S. and Canadian citizens of Japanese, German, and Italian descent around the same time (early 1940s), using similar justification.
With the grain requisition crises, famines, troubled economic conditions, and international destabilization in the 1930s, the leaders of the Soviet Union became increasingly worried about the possible disloyalty of diaspora ethnic groups with cross-border ties (especially Finns, Germans and Poles), residing along its western borders; this eventually led to the start of Stalin's repressive policies towards them, most notably to the national operations of the NKVD and forced population transfer.
In Europe, German minority organizations in Poland and Czechoslovakia formed the Selbstschutz and the Sudeten German Free Corps respectively , which actively helped the Third Reich in conquering those nations. After 1945, this was cited as justification for the wholesale expulsion of ethnic Germans from Czechoslovakia, Poland and the Soviet Union, as well as return to these countries of territories which had been annexed by Germany.
- North Koreans in Japan, particularly those affiliated to Chongryun (which is affiliated to the government of North Korea) may sometimes be seen this way by some Japanese and have been the victims of verbal and physical attacks, more frequently since the government of Kim Jong Il acknowledged it had abducted Japanese nationals and tested ballistic missiles.
- Some Israeli Jews, including politicians, rabbis, journalists, and even historians, have referred to the Arab citizens of Israel, 20% of Israel's population within the pre-1967 borders who are Arabs, as being a "fifth column" inside the State of Israel as Arab Israelis frequently identify more with the Palestinian cause of an independent state.
- Author and Radio Personality Michael Savage frequently claims that in the United States the Fourth Estate has now become the Fifth Column
- In the NBC mini-series, TV series & ABC TV series adaptions of V, a group of rebel aliens and humans call themselves "The Fifth Column".
- In the television series Stargate SG-1, the Jaffa resistance is sometimes referred to as the "Jaffa Fifth Column".
- In the MMORPG City of Heroes, the Fifth Column are a Nazi-themed terrorist organisation that has infiltrated the United States.
- Ernest Hemingway wrote a propaganda play in 1937 entitled The Fifth Column about the Spanish Civil War.
- The "Fifth Column" was a recurring nemesis for the Green Lama in the 1940s pulp stories.
- In the television series Jeremiah, forces of the Army of Daniel that infiltrated the Thunder Mountain complex of the Western Alliance were referred to as the "Fifth Column".
- The Agenda, a current affairs television program aired by TVOntario has a blog colled "The Fifth Column"
Note : Between the Re-Education Indoctrination, and the Current Strategic Systematic Global Agenda, Terrorists are today's Targets Labeled as "A Group of people who Morally Resist and Undermine the GLOBAL GOVERNMENT, GLOBAL RULER SHIP, GLOBAL SUBMISSION, GLOBAL CONTROL SYSTEM. The Conditioning process is aimed to gain subconscious support for the Detainment and persecution of anyone with the attitude they are Morally FREE of the Larger Corrupt Group "Global Governance Agenda", Enticing the Mentality of the Followers of the Larger Group of Global Governance Indoctrinated Puppets to Justify INTERNMENT of others who do not Submit and Follow the "Global Governance Agenda"