This is what I think one of the paragraphs of for the fallen means.
They shall not grow old, for we that are left grow old
They will never get to grow old because they died and won’t be able to die old.
Age shall not weary them, nor the years that condemn
They won’t worry about their age because they won’t be able to live to a old age.
The the going down of the sun and the morning. We will remember them
We will remember them for what they did for us and our country to save us. We will remember them always!