Medal of Honor

i was able to get this achievement as early as the first mission in the part where u have to cut off the lights. Before going into that room you have to take down the door as soon as you take it down rush the guy inside and stab him, then cut the lights and just do the same rush and stab, once you get to the second floor after killing everyone don't take down the last door just reload checkpoint and you'll be back in the alley just repeat until you get it. I believe you get about 7 or 8 kills per reload. ps i was playing on easy making this a lot easier.

The description for this achievement is accurate. The knife kills don't need to be in order. They don't have to be on the same mission. Don't worry about rushing people to try to get knife kills. If you take the opportunities given to you throughout the game, you will most likely get this one.

If you find yourself needing more knife kills, the easiest place to get them seems to be Neptune's Net. You can get 4 before you meet up with Mother and 1 more right after as that part of the mission is all about stealth.