The Trooper Lyrics

Lyric discussion by Mitch1 

Cover art for The Trooper lyrics by Iron Maiden

I don't think it is about WW 1.

It refers to muskets and the use of horses.

"The smell of acrid smoke and horses breath"

It also refers to the Russians which is why I am guessing that you think it is a world war.

I would guess that it is based on the French attempted invasion into Russia under Napoleon.