This achievement is unlocked during the 4th mission of the second Germans campaign, "Teutonic Order".
After destroying the first camp in the mission you come to a field. There'll be a cutscene showing the enemies building traps. A secondary objective will pop up, showing that 6 traps must be taken out. We need to do this without getting detected for the achievement. Arm yourself with some patience, as there are a lot of guards. Remember to switch your unit to defensive mode to be able to spot the traps. I would recommend however, that you put them back in offensive mode whenever they're moving between hiding spots. Furthermore, make sure that when you disarm the traps you don't get spotted as well. You only need to toss a single torch in order to disarm a trap, so keep that in mind.
The traps are placed as such:
2 on the left side.
3 on the middle path.
1 on the right path.
Once you take out the final trap, provided you did so undetected, the achievement should unlock.