The lyrics, by my translation (you can probably get a better trans on the net) go:
The flag high!
The ranks are close (strack)
The SA march with a calm steady step
Comrades, who were shot by the Red Front and Opposition
March with us in spirit
March in our ranks with us
Keep in mind- my German is not translator quality- it is colloquial. I can communicate perfectly with Germans and understand in essence or in context what they are saying. As well, there are certain things I know how to say only in German because I never learned a direct translation to English (English speakers have different euphemisms or ways of saying things).
This song was taught to me in about five minutes time by my wife. I understood it immediately when I learned it and it makes sense when I sing it to myself (which is not often) but it is harder for me to translate in to English in a sense that would be poetic or rhyming. I have the same problem trying to translate Westernhagen's "Freiheit" (Freedom). The song is basically praising Hitler and his army (Horst Wessel Lied- not Freheit)
http://eri.ca/h43/diefahne.MP3
If you cut that and past it in a new window you'll hear the Horst Wessel Song.