Heroin is the most addictive substance in the world. During the Vietnam War sixty percent of American soldiers took heroin. It was available on the airbase runway as soon as new recruits disembarked from their military flight, and it was available on military bases where ordinary Vietnamese cleaners would supply the drug. The military authorities turned a blind eye to this substance abuse until such time soldiers returned to the United States, where the scale of the problem was finally realized. The problem with taking heroin is that it has a ninety-five percent relapse rate. Only five percent of users give up the drug. There was clearly going to be a problem if hundreds of thousands of military veterans returned as lifelong heroin addicts. Only they didn’t. Upon their return from Vietnam fully ninety-five percent of U.S. heroin addicts simply gave up the drug with no medical or psychiatric intervention. This was a complete reversal of the normal trend for heroin addiction. After a large, nationwide study, lasting several years, it was found that the change in environment was enough to delete the desire for the most addictive substance in the world. Simply by returning home, being among friends and family, and changing their environment, was enough to cure those military heroin addicts.