First of all get onto your horse and follow Port to the destination. Make sure to cover him as he moves the cannon into Empire. There are a few enemies as you would expect, but it is nothing you should not be able to handle, just stick to the general path of the cannon and you will be fine. When the cannon is in place, use it yourself to blow up every enemy that you see coming. Next when you have finished head into the laundry building and kill the enemies inside. Make your way though the tunnels, killing all of the enemies as you go. When you reach the end of the tunnels, grab the TNT barrel and place it on the zone indicated and shoot it to blow open the door. (Note: You may want to stock up on ammo here before you progress into the next part of the level). Once you get to Clay, kill the two guys and untie Clay then move on forward. Now its time to take down Hoodoo. There are a few guys around so be sure to kill them, and be wary of the smoke, as it becomes more difficult to see the enemies. Once his men are dead, focus on Hoodoo, he normally stays upstairs, so take a few shots at him with whatever weapon you think is best. (Note: You can shoot those chandeliers so they fall and cause a fire. This is good at taking down Hoodoo when he is hiding). Finally head up to the third floor and kill Hoodoo after the cut scene. Just shoot him a few times and he will die, unlocking the achievement.