Once you reach the upper level, head back into the castle through the hole in the wall. As soon as you enter, you'll be attacked by archers. Use the bow to quickly take out each enemy. Remember to ...

Go inside the castle again using the hole in the wall, and deal with the fire archers there using your bow. On the right side near a hole in the floor, you'll find a treasure chest, open it to get ...

Next comes a proper castle, already built ... it's a game in which you make your base and defend it, with walls and merlons to aid your archers and banners to boost your attacks - or was it ...

This one is for the south curtain wall -- one of the two possible obstacles you must get through to enter the castle. There are archers on top of the wall and your position below makes your units ...