First of all, it's 2 am here, I am tried, and this is all of the sudden, and you completely shift me into this. So I will do what I can.
This poem seems like talking about a weakling following to the battle with a General (or King, depends on what do you mean by 皇) The person was young, puffy eye, bushy tail kind, who is not as brave as you thought. He follow the general (again or king) and going north thru 7000 mile and conquer (渔阳), a place near White River in Beijing. And turn into a fierce fighter, to a point the barbarian wife hear the name and scare.
I don't really understand the last 2 line, I mean I do understand them by word, but I don't see how the last two line (Which talks about the death of 冠軍候 (which is a military honor of sort in west han giving to 霍去病, which credited for slaying 100,000 barbarian) where the last line is about how someone died a hundred time and still will not regret doing it for 漢殤帝 (Which is a king during East Han) related to the rest.
I am here to learn and if you can further clarify this, It would be much appreciated. I will probably be better when I have a more clearer head, but as I finished this post, it's 3 am here and I am too drunk for this.
EDIT 羽林郎 is another poem from East Han which is about a 15 years old hostess that refused a rich a-hole type person's advnace. Which read very much like a person who fight the powerful and win in the end. And I am too tired to care if this is related to your poem, but the general direction is the same.
@coffee_cup
Maybe you want to discuss how "fake" Chinese I am with me here? I am all ear