First thought on reading the title:
If it's going to be blasted out, someone's bound to have already suggested this:
I don't mean the cavalry charge on the bugle.
For an invasion, though, I think it'd be "for all the people ... well, no. This is a song that was written about the people who fought in the Gulf War. It's a song about how shitty war is, and about how shitty war is that it's started by politicians and it has to be finished by ordinary people that don't really want to kill anybody."
If someone actually said "Yo man, we need to spice up this ***** with some jams, dog!" to me I'd be more likely to bayonet him, but, hey, assuming we're playing music, if the invasion's coming the other way and I'm with the right regiment at the time, this:
Wait for 01:50 ... and hold onto yer earlobes for the ending.
If we don't have a sound system? The same song with more voices:
If it's dread you want, though, if you really want something that ought to scare the **** out of the enemy ahead of us, just imagine what's going to happen to those orcs' britches when they hear this mob coming their way:
That enough answers?