In order to earn this achievement, you have to play the "Story -1607 A.D.-" mode and make it all the way to the sixteenth episode of the campaign. It may be take a lot of tries, as some of the fights during the course of the campaign can be cheap, especially when you square off against Nightmare in some cases. But it can be done, so make sure to be just as aggressive as the artificial intelligence and you'll do fine. It took me a day after the game's release to reach this point and earn this achievement.
So again, just make it to the sixteenth episode, then clear it. That's all you need to do! Good luck!