I have read history pretty much my entire life (in fact, my degree is in History), and I’ve read scores of books and articles on Operation Barbarossa, and in particular the Battle of Stalingrad. Brutal is too weak a word for that carnage.
The opening sequence of the first level of the 2004 video game Call Of Duty: Their Finest Hour, while not totally factually accurate, always seems to me to be a good vehicle to convey how brutal the fighting for Stalingrad was. In the first six minutes, you see representations of:
1. Several penal battalions and rural levies charging into German machine gun positions because there wasn’t any other option.
2. A representation of how tenuous the supply chain for the Red Army could be at times (”First man takes the rifle” probably never happened at Stalingrad itself as the men were armed before being sent over in boats, but it *did* happen several times during Operation Barbarossa - and it did happen at Brest Fortress where the Russians only had one weapon per two men!) and how desperate it could be.
3. Pretty accurate representations of political commissars rousing troops to attack, and everyone went despite knowing that they were probably going to be killed by the German guns.
4. Great swaths of infantry getting vaporized, and should they get in among the Germans, no quarter is given.
Nasty, nasty, nasty fight.