It would be within the norms of the day to rewrite the words a bit.

Now this lousy war is over
Oh how happy now is me
Gone the whizzbangs gone the sergeant
I'm off from the infantry

Back to Blighty come next Monday
Sarah needs her soldier boy
Monday's tommy's happy funday
Sarah is my Soldier's Joy

But then again, Spanish Flu was waiting around the corner. I'd love to know how much food shortage led to lower resistance and the deaths which followed.