Given the relatively few Russian territories in WWII the principle is the same.
This is my take on it (I suggest you read the WWII rules on naval pass-throughs for another perspective); I call it the Tank breakthrough rule.
This is based on studying the method of blitkrieg warfare and it’s use of tanks to breakthrough the enemy front line to cause chaos in his rear area. It was particularly effective in the early war against Poland, France and the USSR; in the case of the eastern front because the enemy insisted in placing nearly all his forces on the front line. Gamewise it borrows from the rule we use in Britannia for overruns.
If on attacking an enemy area you outnumber his ground units by at least 2-1, tanks with 2 movement points left WHICH ARE NOT PART OF THE INITIAL ATTACKING FORCE may move through the attacked territory to attack or occupy another enemy occupied/controlled area. This movement is made before resolving any rounds of combat, as it simulates tanks bypassing enemy defences to attack rear areas. This move can only be made if the enemy is heavily, i.e. 2/1, outnumbered in the initial attack.
Of course there are risks with this move; depending on the order in which battles are fought, your blitzing tanks could get cut off with nowhere to retreat to; they can be supported by aircraft but not other ground units hence are likely to suffer tank casualties; they will have no other units to defend them in the case of enemy counter-attack. Tank spearheads which get cut off in this way must be considered out of supply and cannot move again until relieved.
On the plus side this can cause massive disruption to the enemy’s defences, forcing him to plan defences in depth (this is what the Soviets learned to do the hard way). You have to calculate this disruption against likely heavy losses of armour units. And of course you may be able to use breakthroughs to cut off enemy forces from their supply, or prevent them from retreating if you’re using defender retreat rules.
Considering rules such as Panzergrenadiers and mobile infantry; these would give a massive advantage to forces using tank breakthroughs as these can be immediately reinforced with infantry. Perhaps such rules should not be used in conjunction with TBs.
One rule variant that would work is different tank types; heavy tanks with big combat values but only 1 movement, light or medium tanks with less power but the 2 movement allowance needed to effect breakthroughs. So; use heavies, artillery and infantry to engage the main opposition while the lighter armour races through avoiding combat if possible to break through to the enemy rear.
I think this works better than the 2 combat movement rounds idea as it forces the attacker to plan ahead rather than unrealistically wait and see what r1 achieves before commiting his armour to further attacks (in which time the enemy would have the chance to redeploy defences).
