How can I capture Moscow the 3rd time in Tom Clancy's Endwar?

I have been stuck playing on my campaign as the Europeans for ages, as I have won 2/3 battles for Moscow but cannot win the third. Practically as soon as the battle begins my units are getting torn apart by artillery, and I can't stop that because they are guarded by those irritating combat drones which stop my gunships from getting close, and as they are covered by an annoying city wall, it is almost impossible to get to them from the ground. I have some very high ranked units, except for engineers, and all the cles are upgraded to the brink in abilities.