This is a slightly different version than the other one on here. 
I don't know which one is closer to how Phil plays it, but this is my take on it. 
I've included some of the bass runs as well (they're in lower case for better clarity)...

     G              C     /b  D/a
Oh I marched to the battle of New Orleans
       G          C    /b       D/a
At the end of the early British war
    G                  C  Am
The young land started growing
    F                 Em
The young blood start flowing
    Am                 C   D
But I ain't a-marching anymmore

     Am                 G
It's always the old who lead us to the war
C          Em       A
Always the young to fall
    C                              G    /f#      Em
Now look at all we've won with the saber and the gun
C            /b     Am D
Tell me is it worth it all