I am not sure the Geneva Convention was taken very literally on the Eastern Front.
I doubt it's taken seriously by anyone in a real war. When **** hits the fan, people will do whatever is needed to protect the lives of themselves and their comrades.
Now I've never been in a real war, but one movie that I think portrayed it well was the movie "Stalingrad". There was this scene where they were in a large building, shooting at eachother. After a while the shooting stopped and they made a deal that they could both get the bodies of their dead comrades.
The condition was that both parties would cease fire until they managed to carry the bodies away. But since they couldn't trust the enemy, they were constantly watching what the enemy would do.
One soldier was so incredibly paranoid that he thought that an enemy soldier was about to shoot his comrade. So he fired a shot and hell broke loose. Everyone started shooting eachother, even the medics weren't spared.
I can imagine that there's situations in real life where the Geneva Convention asks for a little bit of humanity, but it gets simply crushed by the extreme paranoia and hate towards the enemy.
Now I can imagine that back home that soldier would face the military court or whatever instance oversees the punishment of bad behaviour.
But when I had to choose between my life or the Geneva Convention, my choice would be very clear.