Yup, the promise was a lie...he never intended to rescue those soldiers.
I remember me uttering last night that he's an a-hole, I thought he was nice... I hope he gets a beating...
Akala ko pa naman in an apocalyptic world like that, humans can trust humans to watch each other's back against the walkers. I think now that the moral of the series is that when faced with such a situation (gruesome killings, losing loved ones and all that) the greatest enemy is yourself, not the walkers.