{quote}I was under the impression that the march to the black gates was a somber affair overlaid with a sense of doom rather than something that got the blood up.{/quote}
It is their doom and they all know it. So Aragorn told them to shape up and don't even think about failing personally, He is telling his soldiers that he knows and feels the same way.
I see in your eyes the same fear that would take the heart of me-
I feel your fear/pain, And I wouldn't lead you here to die if it wasn't the only way.
A day may come when the courage of men fails -
Were not going to blow it again (like Isldur)
when we forsake our friends, and break all bonds of Fellowship- Flashback to the Numenorians who allied themselves with Sauron, That was dumb We have already lost much, don't fail now!
But it is not this day, this day we fight We are going to restore our honor, our country, and our freedom.
Basically the King, Christ/Aragorn has returned, Men will act with honour and courage. They will fight to restore all they have lost, Adam/Isldur failed I Christ/Aragorn, WIll restore you, I will make it right.
This day we Fight!