Counterpropaganda.

Project Gutenberg EPUB3 edition Linebarger, Paul Myron Anthony
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This does not mean that propaganda analysis is not needed. Somewhere in every psychological warfare unit there must be an intelligence group servicing the operation. If, for example, the enemy has announced that the candy your aviators are dropping is poisoned (and has proved it by dropping some of "your" candy, made by his black-operations boys and actually poisoned), there is no point in calling him a liar; you may not know for some time whether poisoned candy has been dropped or not. If the enemy commander has shown his troops photographs of prisoners whom your side has taken and "murdered" (according to his well staged photos), it is not a good idea to ask people to surrender without sending along equally convincing pictures of well cared for prisoners. If the enemy alleges that you and your allies are rioting in the streets or stealing each other's womenfolk, or that one of you is doing all the fighting while the other sits around in safe staging areas, it may be a good idea to send along some leaflets showing inter-allied cooperation on your side, or to run a few radio shows on the subject.
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This consists merely of reckoning the enemy propaganda as part of the psychological warfare situation, and of using the enemy as part of the background to your own advantage. The moment you start letting him take the initiative, your propaganda wags along behind his. Tell his people something he can't deny. Let him sit up nights worrying about how he will counteract you. Make him drive his security officers crazy trying to release figures that will please your G-2 in order to reassure his home audience. Really good propaganda does not worry about counterpropaganda. It never assumes that the enemy propagandist is a gentleman: he is by definition a liar. Your listeners and you are the only gentlemen left on earth.

Source attribution

Psychological Warfare, Project Gutenberg eBook #48612

Maximum Performance of Personnel. CHAPTER 5 Psychological Warfare in World War I