Yeah he volunteered to to be solider, so what? Being a solider is not the same thing as being a war criminal and the burden of proof still applies. War is messy and it is entirely possible that this division committed atrocities that haven’t been proven but the mere possibility is not sufficient reason to label him a war criminal. You are de-meaning the term by doing so.
Either you have specific evidence to support your charge or realize you are participating in sensationalism.