Wars are won in the will. That’s it. The people who lose, are simply the people who get fed up first, or who think all is lost.
For example… German couldn’t possibly have occupied ALL of Russia, or Russia, ALL of Europe… but other people submitted to their will, like Poland, France, Baltic States etc, because they did not believe in the possibility of winning against their enemy (Unlike Finland) That’s all it takes.
Simply said, it’s who gives up first. Unless you ABSOLUTELY destroy everything that moves in the entire countryside, vehicles, planes, people etc.

It will be a war like the Russian Civil War, it’s about controlling the urban points, and using the infrastructure that exists in place, mixed with quick air response vietnam style. You don’t need to control the Distance, you just need to control the points at either end of the string.