One comment I got from one of the history shows I watch came from a British WWII vet who said “We were good men who committed acts of unspeakable brutality because the nazis would accept nothing less from us”.
I pass no judgement about what a man must do in the heat of combat. But I do so on a military person who murders non-combatants in a situation where it is not the heat of combat.
I understand the bombing of German and Japanese cities. I understand machine gunning Japanese troops in the water whose transport was sunk with Japanese held land nearby.
I can find no excuse for what the Soviets did to Polish officers in the Katyn Forest, just as an example.