The culture of war and death that was prevalent from 1940 til 1945 is hard for many to understand. Even though it is prevalent to this day. The peoples of the participating nations were able to endure much hardship, to the participants it was a feeling of national survival. Many units involved became a part of the culture of war. All sides wanted to win. The Germans were able to deal death and destruction for national survival, and the Brit's did the same. The Americans were angry that they were drug away from their peaceful life to fight in Europe and the Pacific and fought with great anger. Propaganda on all sides was great and caused the enemy to become almost non-human beasts. In reality it is an essential part of war to be able to disassociate the enemy with good human characteristics. The propaganda used was a great success, maybe too successful. Many Americans still consider Germans to be Nazi's in the back of their heads.
Situations like the strafing of civilians, the punishment of civilians for partisan efforts, the terror-bombing of cities, the collection of gold teeth( prevalent in all theaters, USMC, etc), and the shooting of members of Waffen-SS units, are the norm and not isolated incidents. In fact the ferociousness defines the war.