Here is a trailer for the movie:
How is this relevant to the thread title? Well, in the movie it is revealed that strong hallucinogenic drugs were used on the soldiers to make them more aggressive. The drug was tested (allegedly) in the actual war, though the pentagon has always denied such a claim. But we all know how reliable their word is for things
BZ wasn't the only chemical drug used by the American government during the Vietnam War. Another chemical agent they unleashed on the Vietnamese people was Agent Orange. This was a supposed herbicide dumped on Vietnam but had devastating effects which modern Vietnamese are still feeling the shock waves of today. "Over 300,000 U.S. veterans and over 400,000 Vietnamese people died from exposure to Agent Orange from 1962 to 1971." - https://my.clevelandclinic.org
And we can't forget: something I mentioned to @Cornfed and @gsjackson in another thread. The cloud seeding America used to prolong the monsoon seasons. I've read before this caused many people to starve.
Why were these atrocities committed? Why was the war in Vietnam necessary?
The reason was because of ideological differences between Capitalism and Communism. Two ideologies which are toxic and caused the deaths of so many people. @69ixine posted some good videos of Capitalism and how toxic the ideology is that some of you should check out.