OK, that's enough of the grade-school primer; it's time 
to get down in the mud. Let's take a look at the 
Russo-Finnish battle on the Karelian Isthmus, which can 
be tough to win as the Russians. The victory requirements 
are to take two southern cities (Summa and Taipale), 
the northwestern city of Tali and its port at Viipuri, and 
finally the northernmost city of Sortevala. The problem is 
the Mannerheim line: a rigid defensive line of pillboxes 
and World War One-era forts bisecting the Isthmus. 

First, you'll need to understand your forces, which are a 
mishmash of good and bad units. The conscripts and auxiliary 
units are awful, and the best (and most historical) use for 
them is to charge pillboxes and divert Finnish fire - in 
effect, these troops are cannon fodder. Also useless are the 
BT-5 and BT-7 tanks, which seem to be made of papier-machŽ. 
If you use them, you'll lose. Upgrade as many as you can to 
KV 1/39s; they're slower, but have much better defense and 
attack ratings. You'll want to start with five or six of them. 
You'll also want to get another engineer unit or two, which 
you can do by upgrading a Regular unit. 

Lay some artillery fire on Terijok, near Leningrad. 
You have two cruisers and plenty of artillery, so you can 
weaken it enough for the adjacent conscript unit to take it 
easily. This clears the road to Summa. You'll need to organize 
two battle groups (Eastern and Western) based around the KVs. 
Divvy up the infantry, cavalry, and artillery between the two. 
The Western group will push towards Summa, then up to Viipuri, 
while the Eastern will hit Taipale and then make a dash for 
Sortevala. Any extra units should go with the Western force. 
Mount the bridging engineer and send him north with the 
cruisers, and mount the paratroopers and send them as scouts.