An Allegory, Not An Adaptation
When asked about his influence on the film, Milius maintains that he wanted to use Conrad’s original story as more of an allegory than a direct adaptation. He said that following the book would have been “too simple” and so decided to take some elements and ideas, while introducing whole new settings, plot points, and characters, using his own knowledge and experiences along the way.
Marlon Brando, Martin Sheen. Photo By Marlon Brando, Martin Sheen in 1979
He based the character of Willard (Sheen) and part of Colonel Kurtz (Brando) on one of his own friends, Fred Rexer, who claimed to have actually experienced the scene described in the film by Colonel Kurtz where the arms of villagers were sliced off by Viet Cong members, although some scholars say that there is no proof of this happening.