Imagine being an American soldier sent to Vietnam to fight the militarized Marxist Communists there. The Vietnam War provides many examples of such a plight. Now consider how much worse it would be to be sent into a seemingly constantly rainy, hot and humid jungle deep in Cambodia to assassinate an American colonel because he is a renegade Special Forces military officer who has gone insane. Just in case this is not dire enough, simply add in that he has the local village protecting their god with weapons. Surely safer secret military missions exist than to assassinate an insane former special-ops man with a small army of devotees. This is the central plot of the 1979 film, Apocalypse Now, directed by Francis Ford Coppola, who had directed The Godfather earlier that decade. Behind the plot of Apocalypse Now is a dichotomy wherein human nature itself is bifurcated into a dichotomy of good and bad. This is interesting because some of the characters may fall in between, suggesting that human nature has a gray zone in which most of us live.
The full essay is at "Apocalypse Now."