Matteus,
Red it once again and I want to add a few comments, if you do not mind!

First of all I think it is the best story you have ever written. The persons are real, not TW stereotypes. You describe their feelings and thoughts very realistic as well as the situation in a real army. That is very good. If Petersburg is the scene, you could add more depression. They should have known that the war was lost. However, they refused to accept it and kept on fighting. Maybe some "there will be a lot of mothers in the north who cry for their sons before this war is over".

Before the mining operation there wasn't there an attack from the North were the soldiers refused to attack? The moral of the North was poor then too and maybe the Rebels know that as well.

But again, this part of the story is excellent, I like it a lot.

If memory serves the explotion of the mine was a big surprise, not only to the Greys but also to the Yanks generals. Why do you take the surprise away? You write that the defenders expect a mine and so the story is predictable.

I think you have to better options:
1) They do not know anything. They are waiting for the Yanks, determined to fight until the bitter end. Then, suddenly, there is the big bang, chaos, noone knows what had happaned.
2) They know what the Yanks are doing. They know that there will be the blow someday and that they do not have a chance to survive. Nevertheless they decide to stand.

P.S.: Your stories always show the glorious side of war. although you also show that there is a dark side. But glory dominates, maybe the dark side even emphasises the glory. My stories are the opposite. I know there is courage and pride but the dark side dominates. In the end the dark side makes the pride and honor absurd.
Maybe we should put our stories together and publish a book with our short stories