Seuss' "Butter Battle Book" is an allegory for the Cold War. It shows that sometimes the smallest of conflicts can lead to major, unnecessary battles. The Yooks and the Zooks argued over how to butter bread, while the U.S.A. and the U.S.S.R. argued over how a government should be run.
The united states entered WW1 after Britain intercepted the telegram and showed it to American officials. This made America mad, henceforth causing troops to be shipped to Europe.