I found a very nice spot to farm for this. Sorry if I can't provide a video, but I do not have recording hardware for the x360.
You're gonna do (or replay) this at a Business Rival mission. I had this mission available after DNA Sequence 5. I did some Business Rival missions and then I came to this one at one point. I do not know if it's required to do other missions like Ship or Slaves to make this one available.
Anyways, to replay it if you already did it, go to menu, DNA, Business Rival and select it:
The mission is called "M. de Vandal's Harbor"
After a short sprint to the starting point you will get attacked by waves of Musketeers, while their boss is just standing back. There are plenty of waves and should you not get the achievement in the first try, you'll certainly unlock it in the second one as you get chance to do a lot of human shields.
Either try to keep one guy alive to use as human shield for the next wave, or just grab the Captain guy (the one with different hat and no gun) that comes at the start of most waves (he doesn't come always).
Just make sure to not leave the mission area, as it's quite small.
I got this replaying this mission just twice. Popped right after a few waves on my second go, so I got a lot on the first go.
Not sure if this is necesary, but I suggest to complete the memory in order to save properly if you didn't get it in one single go.
Goose9847L: you can check how many enemies you've killed with human shield by going to Start Database Stats Fights and Kills
its the 6th item on the list
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