Sounds good, but that totally leaves out the fact that eaven if the country has plenty of supplies, there's always those logistical problems.
What I'm trying to say is eaven a rich country with everything to give it's troops, and all the transport utility available, will have logistical problems. Equipment not getting there in time, or getting damaged on the way etc.
When troops are in combat far away from their home, where the supplies come from, things, that are unpredictable will no doubt happen, and getting those supplies to the troops, to help their predicament, ofcourse takes longer from distance, thän near by, thus giving a penalty to the attacker.
Heureka! How about this: Instead of taking more supplies (or maybe that aswell), troops far from "base" could have slower organization recovery speed to point out the logistics problem?