Like many U2 songs there are probably many levels of understanding.
It could be about a soldier coming home from war, but i always think of refugees walking day after day after day
"through the sleet and driving snow"
"as we live by the side of the road"
"dislocated, suffocated - the world grows weary of its own"
Every time I listen to the song (which is quite often !)I think of the horrendous dislocation on Kosovo and Bosnia.
It is long and quite relentless - it never slows, never a break, like the journey of a refugee or a soldier.
It could be about a soldier because he finally reaches home, but I cannot get this vision of displaced people trapsing across a barren landscape when I hear it.
Anyway these are just some musings
It is one of my favourite U2 songs ever!! as is the rest of Unforgetable Fire