"The Butter Battle Book," which was published in 1984, may have been Geisel's most controversial work. The story revolves around two mutually antagonistic cultures called the Yooks and the Zooks, a veiled reference to the United States and Soviet Union. Both sides are divided on what should be the trivial issue of whether bread should be buttered on the top or bottom of the slice. The divide leads to an arms race and the book ends with both sides facing off against one another on top of a wall, an allusion to the wall in Berlin. The final page is blank, inviting readers to finish the story themselves.
The story tackles the heavy issue of nuclear annihilation and mutually assured destruction. Despite the subject matter, the book was popular primarily among adults and held a place on the New York Times' best-seller list for six months, according to BBC News.
Libraries across the country yanked the book, partly because of the downbeat ending that could frighten younger children, but also because of the story's political messaging.