I had to read more than 10 exercise books on castles lately and this one comes on the top of my list. The illustrations it contains are numerous and extremely well done. So, in the section of castles in war, you'll see the classic siege illustrations, but additionally you'll find ones for siege weapons, mining, counter-mining(!) and dirty war tricks(!!).
If you want to let your mind wild into the world of castles, this is the book to get.