I watched a documentary on YouTube about Unit 731 and while not a Movie really it was very disturbing. Unit 731 was a biological warfare research facility located in main land china and what they did to people was terrible. Medical experiments on men, women and children and even whole villages. The US let them all off the hook in exchange for their research results too. I also listened to a Podcast on the Rape on Nanking and both of those were more disturbing than any war movie I've watched. Maybe the most disturbing thing I've learned about was the Rwandan genocide. That stuff was crazy.