Copied from http://www.poplyrics.net/waiguo/soundtrack/coldmountain/005.htm

YOU WILL BE MY AIN TRUE LOVE
Written by Sting
As sung by Alison Krauss

You'll walk unscathed through musket fire,
No ploughman's blade will cut thee down,
No [cutler's horn?][cutlass war?] will mark thy face
And you will be my ain true love,
And you will be my ain true love

And as you walk through death's dark vale,
The cannon's thunder can't prevail,
And those who hunt thee down will fail,
And you will be my ain true love,
And you will be my ain true love.

Asleep inside the cannon's mouth,
The captain cries, "Here comes the rout,"
They'll seek to find me north and south,
I've gone to find my ain true love.

The field is cut and bleeds to red.
The cannon balls fly round my head,
The infirmary man may count me dead,
When I've gone to find my ain true love,
I've gone to find my ain true love.

[I've compared several copies I've found on the Internet, and chosen the words that make most sense to me. Some copies have obvious mondegreens. One error that all versions had was "death's dark veil." I'm certain this should be "vale" meaning "valley". Since I have no recording to listen to, I've been unable to determine what line 3 should be.]