Enemy Units Passing Through Lines

[Crow]

I am having serious trouble with units just passing through my defended lines and into the territories behind them without a fight.

Mostly this is happening on the eastern front with Russian and Serbian units. Often when I send another unit to catch them, they will occupy the same territory and not attack them, sometimes even of offensive posture.

There must be some way aside from placing units on offense (and giving up terrain and entrenchment bonuses) from stopping these buttholes from casually strolling through my lines. So what is it?

Please help, because I'm considering shelving this game otherwise.

[Durk]

This is a challenge, are you playing against AI or pbem? This does make a difference. AI can move in ways live players cannot.

[Crow]

This is a challenge, are you playing against AI or pbem? This does make a difference. AI can move in ways live players cannot.

I am playing against the AI, and I have indeed been seeing the AI do a lot of things that I cannot.

[Durk]

Look at the loyalty of the regions. If you can have at least 50% loyalty, this might stop it.
This is a real challenge.
Your offensive stance is a good idea. But also remember if they pass your lines without obtaining supply, they will wither for lack of supply.