At the end of The Butter Battle Book, the Yooks and the Zooks make an alliance to share the land and eliminate the wall. The bomb is never dropped because the Yooks and Zooks notice that it will only cause problems and harm people. They decide that both sides could have one big land instead of fighting against eachother. They then notice that it doesn't matter whether someone has their bread with the butter side down or up. Everyone will live in peace together and live happier ever after.