For the past nearly 250 years, when the United States faced a grave threat, our people rose up and sacrificed whatever it took to defeat it. From the American Revolution to the Civil War to the menace of the Nazis or Soviet communism, we were willing to do what we had to do to defend what we valued most about this country.Today, as it did once before, in 1861, the greatest peril confronting the country comes from within. Then as now, it was a threat that sought to divide America, and it was a th