There are many things that people don't agree about concerning World War II. But you would think that a seemingly objective fact, like when Pearl Harbor happened, would be incontrovertible. For someone like Marah, talking to her mother after the war, however, even the date was a point of disagreement.
Everything depends on your point of view. Even the date when something happened. Maybe if more people were able to shift their perspective, then we would have a lot fewer disagreements.
