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?