At 8:46 a.m., in front of reporters, he and Michelle Obama observed a moment of silence outside the White House to mark the minute and hour when American Airlines Flight 11 flew into the World Trade Center.
Then, in front of reporters, the Obamas moved to the Pentagon. They arrived before 9:37 a.m. so Obama could lay a wreath to mark the minute and hour when American Airlines Flight 77 flew into that building.
On the way back to the White House, in front of reporters, they stopped at Arlington Cemetery to visit the graves of servicemen killed in Iraq and Afghanistan.
At 2:15 p.m., in front of reporters, they departed for Walter Reed National Military Medical Center to visit wounded troops.
At 3:40 p.m., Washington, D.C., time -- or 9:40 p.m. Benghazi time -- the Obamas, according to the White House schedule, were still at Walter Reed. At that moment, terrorists launched an attack on the U.S. consulate in Benghazi.
"The attack began at approximately 9:40 p.m. local time," Deputy Assistant Secretary of State Charlene Lamb said in written testimony presented to the House Oversight and Government Reform Committee. "Diplomatic Security agents inside the compound heard loud voices outside the walls, followed by gunfire and an explosion. Dozens of attackers then launched a full-scale assault that was unprecedented in its size and intensity."
State Department officials in Washington learned of the attack almost instantly. "I could follow what was happening in almost real-time," Lamb testified.
The White House learned no later than 4:05 p.m. -- or 25 minutes after the attack started. The State Department at that time sent the White House an email. The subject line: "U.S. Diplomatic Mission in Benghazi Under Attack."
The Obamas were scheduled to arrive back at the White House from Walter Reed at 4:50 p.m. Reporters could cover their arrival if they gathered at the North Doors of the Palm Room by 4:30 p.m.
At 5:00 p.m. -- an hour and 20 minutes after the attack started -- Obama was scheduled to meet in the White House with Defense Secretary Leon Panetta and Vice President Joe Biden.
On Tuesday, I asked the Defense Department three questions: Did this scheduled meeting take place? Was Panetta aware then that the diplomatic mission in Benghazi was under attack?
Did Obama use the meeting to discuss with Panetta what should be done to defend the U.S. personnel under attack?
"Secretary Panetta met with President Obama, as the White House-provided scheduled indicates," Lt. Col. Todd Breasseale, a Defense Department spokesman, responded. "However, neither the content nor the subject of discussions between the president and his advisors are appropriate for disclosure."
At 11:00 p.m. Benghazi time -- as Obama, Panetta and Biden were beginning their White House meeting -- U.S. agents abandoned the consulate in Benghazi and headed for a nearby "annex." They took the body of State Department communications specialist Sean Smith with them, but left behind Ambassador Stevens, whose whereabouts was unknown.
"The agents made a final search for the ambassador before leaving in an armored vehicle," Lamb testified.
The U.S. agents made it back to the annex about an hour after Obama, Panetta and Biden had started their meeting. "They took heavy fire as they pulled away from the main building and on the streets outside the compound," Lamb testified. "Two tires were blown out, and the bullet-resistant glass shattered but remained intact. Upon arriving at the annex around midnight, they took up defensive positions, including on the roof. Shortly after their arrival, the annex itself began taking intermittent fire for a period of time."
At 6:07 p.m. Washington time -- an hour and seven minutes after Obama, Panetta and Biden started their meeting -- State sent another email to the White House. Its subject line: "Ansar al-Sharia Claims Responsibility for Benghazi Attack."
Some time in the "early morning" of Sept. 12 Benghazi time, as the attack continued, security reinforcements arrived from Tripoli, about 400 miles by air from Benghazi. "Shortly after they arrived," Lamb testified, "the annex started taking mortar fire, with as many as three direct hits on the compound."
Undersecretary of State for Management Patrick Kennedy conceded to the Oversight Committee that some "other government entity" has a 50-minute video of part of the Benghazi attack.
Five days after the Benghazi attack, Susan Rice, the U.S. ambassador to the United Nations, described the attack as an unplanned reaction to an anti-Muslim video posted on YouTube. "It began spontaneously in Benghazi as a reaction to what had transpired some hours earlier in Cairo, where, of course, as you know, there was a violent protest outside of our embassy sparked by this hateful video," Rice told CBS News.
On Sept. 25, Obama told the U.N. General Assembly, "There is no video that justifies an attack on an embassy."
On Oct. 18, Obama told Comedy Central, "If four Americans get killed, it's not optimal."
On Friday, our president told KUSA TV in Denver that "the minute" he found out about the attack in Benghazi, he ordered subordinates to "make sure that we are securing our personnel and doing whatever we need to."