Start working on causing that flood...

You turn back from where you made your cold camp within a few hundred yards of the wall in the surrounding forest. Much as you wish it were otherwise the general gets to live out the rest of today, and probably a few days longer, but his **** is fore ordained, and not by anything so clean as a gunshot to the back of the head either, he dies by flood. Like the wrath of God upon the iniquities of men during the first age of the world you will kill him, and when you do not all his powered armor or psychopathic guardians will be able to stop it, because he is bed ridden and if the water does not kill him the explosion assuredly will. There is another question you need to ask yourself though: how long can you hold out to make this happen? How many days can you stretch your food supply while you search for what you need and still be strong enough to swim the flooded mine and plant the charges?