To get this achievement Captain Drummond must give you a Drangleic Helm.
Captain Drummond is located in the Memory of Vammar. To access the giant memory you need the Ashen Mist Heart (story related).
Before you go to see Drummond, begin by going to the Memory of Jeigh. To get here, go down the ladder from the Cardinal Tower bonfire in the Forest of Fallen Giants and then across the bridge. Across the bridge is a door (You must have beaten the Last Giant to open this), go through and turn left. You should come to an open area with a King's Gate. Equip the King's Ring and enter, take the bonfire. Continue through outside to see a Giant Tree. Examine the tree to enter the Memory of Jeigh. In the Memory of Jeigh you must kill the Giant Lord, then leave.
Note: Make sure you summon Benhart for this fight so you don't miss his achievement, see the 'Moonlight Greatsword' guide for details.
Now that you have killed the Giant Lord, go back to the Cardinal Tower bonfire. From here go to where the ballistae are, rather than go into that room, go into the area opposite it and go through the right archway here. You should see a Giant Tree and two hollow soldiers attacking it. Go up to the tree and examine it.
Now you are inside the Memory of Vammar. You start in a mineshaft, follow it along until you reach a room. There should be many bodies on the floor. To your right, lying down is Captain Drummond. Talk to him and he should give you his equipment.