Is it worth a fight?

Library trip. My kids have a list. They are to get 1 biography, 1 book of poetry, 1 chapter book and then a book to do a book report on. I allow them to select their topics. Des, my gamer head boy, who will do ANYTHING to not have to leave the world of WOW, comes over and proudly announces that he has found his book report book. He is way beyond excited. He spins said book around in front of me ....the cover is graced with beautiful photos of armor and swords. Helmets, mail, knight battle helmets. The History of Armor.
He is standing there puffed up like a thanksgiving turkey. He is watching my face to see my reaction. Yeah......I decide that it isn't worth the fight. Especially if I can swindle an enthusiastic book report out of that subject.