"Secret Army" is a television drama made by the BBC and the Belgian national broadcaster BRT (now VRT). It tells the story of "Lifeline," a fictional Belgian resistance movement in German-occupied Belgium during the Second World War dedicated to returning Allied airmen, usually having been shot down by the "Luftwaffe," to Great Britain. Three series were broadcast on BBC1 between 7 September 1977 and 15 December 1979.

"Secret Army" was created by Gerard Glaister as a follow-up to his drama series "Colditz." Glaister was a former RAF pilot and his experiences provided the inspiration for the series. "Lifeline" loosely resembled "Comet line," a real-life resistance organization in occupied Belgium and France during the Second World War. The scripting of one of the principal characters in the first series, John Curtis, was influenced by the experiences of the series's technical consultant, Group Captain William Randle. Randle had himself escaped from German-occupied Europe in 1942 and was later Keeper of the Battle of Britain Museum.

The series followed the timeline of the war to show how it affected Belgium. Filming took place in Belgium, with the assistance of BRT. Other locations were in London and Norfolk.

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