This came up in last night's game, the Wildlings attacked and we failed, so everyone had to lose 2 units. The question was, if the unit you lost emptied the land you were in, could you place a Power Influence to keep control of that land?

-shnar

Oh, and speaking of Wildling attacks, when you lose 2 points worth of units, can you downgrade a Knight to a Foot Soldier as one of the lost points?

-shnar

The answer to both these questions is No. The FAQ answers them in slightly more detail. I'd have copied/pasted the exact FAQ entry, but it turns out that A Game of Thrones is one of the few games I don't have a PDF copy of the rulebook to, and FFG's site isn't working.

If I remember the rules correctly, you can only leave an influence token to keep an area after a successful march, thus losing the control of an area after a wildling attack.

Specifically, you place a power token when you "leave" an area. It's been FAQ'd to state that if you march into an attack and lose everyone, you can still place the token. But when they get wiped out from something other than you Marching troops from the area, you can't place a power token.

Quoted directly from the offical FAQ

Wildling Attack
Q: When you lose a battle to the Wildlings, if you surrender
a unit, leaving a region vacant, can you place a power
token in the region to retain control of the region?
A: No.

Q: When you lose a battle to the Wildlings, can you downgrade
Knights to Footmen to pay for the muster points
instead of removing units?
A: No. You can only remove units to pay for Wildling
losses.