Thanks, Keith, amazing links. I will read and try to absorb them.
Sam, thanks. My friend is knowledgeable but that does not mean he is always right. Reflecting on it, it seems his contention was that the Russians did not attack in Line formation; perhaps that fits with what you have said. I'll investigate it further.
Now there's a separate issue, which I raised with him but we didn't settle: supposing that he is correct, should the rules of the game force you to behave in that way? Some games are designed according to the principle that if you don't play the way the designer wants you to play, you are punished. To me, this can be very limiting. To him, if you're allowed to do something that was historically not done, the game is ahistorical. I can see both sides of this. If my position is taken to the extreme, a game might be played in a way completely unconnected to its subject matter. If his position is taken to the extreme, hypothesis and play are subjected to a tyranny of dreary historical facts.
So if Russians didn't attack in Lines and I choose to do so, am I the most brilliant Russian general or merely a knavish violator of historical decorum? And if we were talking about an Operation Barbarossa game, would I as the Russian be obligated to wastefully throw away my men's lives and mishandle my military assets, or would I be allowed to make actually smart decisions?