Everyone argues every once in a while. Think about the last time you had an argument.
Chances are you were arguing about one thing, but the argument was really about something else altogether, something that had been building up and building up. The buildup is the backstory. The same process may take place between nations. In 1846, Mexico and the United States went to war. The results of that war coincided with the beginning of California and other western territories, but the backstory began decades earlier. . . .