Level three of the Axis campaign takes you to the snowy, rugged landscape of Western Russia to defend your base against 30 waves of purely ground units, still free of air support. Two entrances exist on this map, coming from the northwest, heading southeast making a curved Y towards your base.
Like the previous mission, turret placement should be focused along the converged path as to allow all of your guns to fire on all the units that you will face to avoid wasted effectiveness. There is some southern high ground that can boost the range of your Cannons but is a bit too far from the path for Machine Guns.
From the get go up through wave ten is much like the previous missions, focusing on getting some Machine Guns up around the converged path. Try to get at least three fully upgraded by the end of level 10.
With the increased flow of funds from the additional enemies that come to attack your base in waves 10 through 20, build a single Firestorm against the path, a fourth fully upgraded Machine Gun and a couple of Cannons along the southern high ground. The Firestorm helps slow down the enemy for your other turrets to lay more shots into while burning away their armor.
By the time you reach the end of level 30, try to have 5 level 2 Cannons to take out the heavy armor, building nothing but these at this point in the level. As long as these are also along the converged path, this method is sufficient to stop the enemy.
Victory Point Spending
Since the aircraft levels will be approaching soon, at this point I choose to put a single victory point into the Anti Aircraft with the second into the Repair upgrade. You can optionally skip the AA point for something else, using it instead the level after next as mission 4 has no aircraft.
The current ranks of unlocked items are:
MG 3, Cannon 3, AA 2, Firestorm 1, Buy 1, Repair 1