User blog comment:Maki Kuronami/Lesson 17: Food fights elevated into an arm form./@comment-24181684-20140725005107

The "Third Crusade" may very well be exactly what it says it is, a book relating to the events of a "Third Crusade", that took place before the Human-Faunus War and was one of their "solutions" the humans had to be rid of the Faunus.

This may also explain why the store owner (forgot his name D: ) doesn't sell the book, what with him being a Faunus, he probably didn't want to sell something that casts his race in such a negative light. This may especially be the case if it parallels the Third Crusade in reality, as that crusade was one the more "successful" crusades (next to the First one at least).