presiding over such a divided country making former president's george w. bush's speech in shanksville, pennsylvania, on the 20th anniversary of 9/11. makes it key. gave the keynote address and in the speech gave a powerful appeal for national unity, like what we saw after those attacks. >> as a nation our adjustments have been profound. many americans struggled to understand why an enemy would hate us with such zeal. the security measures incorporated into our lives are both sources of comfort and reminders of our vulnerability. and we have seen growing evidence that the dangers to our country can come not only across borders but from violence that gathers within. there is little cultural overlap