How about a Partisans card that could be played on a bonus area resulting in a partisan uprising in the territory that could require a garrison with the troops stationed there attriting by 1 or 2 armies a turn until it becomes neutral again and then would have a large neutral force?

Uhm what?
I try to make sense of that sentence, but I can't really.
What I get from this, is that you want a card which can blockade an opponent's territory.

If that's what you mean, I don't think that's such a good idea.

its not easy but i think it works this way :

1- play on a neutral territory

2- that territory generates partisans that attack ( 1-2 a turn) an opponent territory nearby.

3- the territory became non belligerant again but with a larger force

its an abandon on steroids

Sorry if not clear. I am suggesting that just as the French, Polish and Yugoslav partisans harrassed the Germans and tied up their troops behind the lines, that there be a card for Partisans that is played on a Bonus Area controlled by an opponent that will then cost an army or two each turn to "pacify" each of the territories in that bonus. If the garrison is too weak, the garrison would be wiped out and, instead of the player that played the card controlling it, the territory would become neutral with a strong defense for anyone trying to take it later because of the local opposition to invaders. The card would lapse if the partisans did not wipe out the garrison in a specified number of turns (i.e. the garrison managed to subdue the local partisans).

Partisans would be an intriguing concept though I don't know how best to implement it or inform the victim of it.

They certainly have been a major aspect of modern and past warfare... from the US Revolutionary War to the Napoleonic War (Spanish and Portuguese partisans killed more French than their respective armies I'd wager) to even Iraq and Afghanistan (debatable but they seem to me to be closer to partisan than established army)