Excellent suggestions all. I suspect that I'm not the only new player who is learning the system (I learned about the game through the Ipad apps, and know of several others).
Patience and careful planning certainly seem to be virtues when breaching a fortified line, along with copious artillery
Of course, the delayed disruption rule (which most seem to prefer) makes the prospect a bit more difficult.
The game does a great job of representing the limitations of the Russian tank brigade organization of the time. They are mobile enough to do some neat things if you can break through, but that's a big if. Not terribly great in a combat role though.