Do any of you guys have/know of any books that contain old illustrations of plans for wooden walls or forts? I'm looking particular for ones that are semi-circular and concave with protruding sharpened posts.

I don't have the books anymore since they went *poof* in a fire. I had books on fortifications, specifically motte and bailey that when they didn't have a water moat they were protected sometimes during siege by a row of stakes, sometimes which were set into the walls as well as in the dry moats. Wish I could remember the name of the book.