My reasoning for this being they are by far the strongest infantry unit in the game. I chose exclusively Nord for the first half of my game, and concentrated on getting as many huscarls as possible. First decision to make is what you want the make up of your army to be. I did this on my first attempt becoming a vassal of the birds initially.
In general information on obtaining this is fairly scant. The one solution already here I feel isn’t deep enough, I certainly could have done with more information prior to my attempt. I have just obtained this achievement and decided I would write an in depth guide.