During The Garden mission, you'll be attacked by a large 'Bear'. After fighting it off, it will run away and crash through a wall, at which point it will be attacked by a few Watchmen as you approach. For the sake of ease, make sure you switch to an automatic weapon with military grade ammo once it runs away. When you approach it and the Watchmen jump onto it, shoot them off to save its life, gaining a CRUCIAL moral point (to work toward Redemption at game end) as well as this achievement.
Check out the video below for a full playthrough of the game showing all collectibles, miscellaneous achievements like this one, and the Moral Points I obtained (I skipped a lot of them) in order to get the Redemption achievement. The Garden mission starts at timestamp
1:58:54.