I think Clint Eastwood was trying to show that not everything was black and white like they ususally make war movies to be. He showed the one Japanese man who was a baker before being drafted was less than thrilled about being drafted and also being put out of business by the military police. He also showed he was less than thrilled about putting a grenede to his head in the cave when all the others did so. The two that escaped the cave almost got their heads chopped off by their own people but were saved by the same commander who saved the Marine. There really were times when US Forces killed and abused captives both in the Pacific and Europe. The Allies were not always good guys in white hats.
When Greg Boyington was captured by a Japanese submarine, he said he was treated well. It was not until he was put ashoure and the army got him did the abuse begin.
I think the message of the movie was that war is such a waste, no matter who's side you are on. Das Boat gave me the same type of feeling. Why do thousands of young men get hurt and killed for old men and their stupid ideas on how the map should look. If that is anti-war then I am anti-war and proud of it ! You sound like your user names part in the movie thinking war is great just for the sake of having a war.
Ok I am off my soap box. I thought it was a good movie.
