Whether in battle or in the forest chapel, what was there to greet Henry?

Upon reaching a chapel, Henry is met by a gruesome sight:

"He was being looked at by a dead man who was seated with his back against a columnlike tree. The corpse was dressed in a uniform that had once been blue, but was now faded to a melancholy shade of green. The eyes, staring at the youth, had changed to the dull hue to be seen on the side of a dead fish. The mouth was open. Its red had changed to an appalling yellow. Over the gray skin of the face ran little ants. One was trundling some sort of bundle along the upper lip."