Player Embed Code: Download Embed Share Austin, Milley Participate in 9/11 Ceremony Defense.gov Sept. 11, 2023 | 59:00 Secretary of Defense Lloyd J. Austin III and Army Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, speak at a ceremony honoring the 184 lives lost in the 2001 terrorist attack on the Pentagon. The event is being held at the National 9/11 Pentagon Memorial.