Airmen prepare to lower the colors during a 9/11 memorial ceremony Sep. 11, 2014, at Joint Base Charleston, S.C. The flag was flown at half staff through out the nation in memory of the victims of 9/11. The retreat ceremony was a poignant reminder of the events of 13 years ago, and the continuing efforts today’s military is making against the War on Terrorism. (U.S. Air Force photo/Airman 1st Class Clayton Cupit)

Joint Base Charleston Airmen stand at attention in preparation for a 9/11 memorial retreat ceremony Sep. 11, 2014, at JB Charleston, S.C. The retreat ceremony was a poignant reminder of the events of 13 years ago, and the continuing efforts today’s military is making against the War on Terrorism. (U.S. Air Force photo/Airman 1st Class Clayton Cupit)

Airmen lower the flag during a 9/11 memorial retreat ceremony Sep. 11, 2014, at Joint Base Charleston, S.C. The retreat ceremony was a poignant reminder of the events of 13 years ago, and the continuing efforts today’s military is making against the War on Terrorism. (U.S. Air Force photo/Airman 1st Class Clayton Cupit)

Airmen fold the American flag during a 9/11 memorial retreat ceremony in remembrance of the 9/11 attacks, Sep. 11, 2014, at Joint Base Charleston, S.C. The retreat ceremony was a poignant reminder of the events of 13 years ago, and the continuing efforts today’s military is making against the War on Terrorism. (U.S. Air Force photo/Airman 1st Class Clayton Cupit)

Master Sgt. Jennifer Crerar, 628th Security Forces Squadron first sergeant, delivers a speech during a 9/11 memorial retreat ceremony Sep. 11, 2014, at Joint Base Charleston, S.C. The retreat ceremony was a poignant reminder of the events of 13 years ago, and the continuing efforts today’s military is making against the War on Terrorism. (U.S. Air Force photo/Airman 1st Class Clayton Cupit)