George, the meaning of the last libation is this...

It is said the soldiers believed a man died twice. Once, when his body died, the second death was when his name was spoken for the last time. They soldiers would drink a toast after each battle to remember those they had lost, both in the battle and in past battles. It was their way of keeping the memory of their comrades alive.

Now, what is the source of this?... I can't say except that it is a tradition. A worthy one I believe. By keeping the men's memory alive they are still with us in our hearts. As I once saw it written.... one of the secrets to immortality is to be remembered!