On the East front. Latter half place unknown

Panzer IV

East front 1941,  Ukraina, Dnjeper river. The German artillery.

German assault guns

During WWII,  one problem a tank crew had was enemy infantry getting close enough to the vehicle to enter a blind zone -- the area immediately surrounding the tank that any soldiers inside simply couldn't angle to shoot at. And so the Germans developed a rifle with a curved barrel so that riflemen inside the tank could just stick the gun out of the tank hatch and fire at potential enemies.
Not only did the bullet fail to hilariously explode on its way out of the floppy dong rifle, but it would neatly fragment in the curve, creating a devastating shotgun-like effect. Later prototypes, complete with periscopes, were developed for other infantry units to shoot at Allied soldiers from behind cover (and presumably to teach any loitering smartass ducks a lesson in manners).

