Special tactics Airmen depart Lackland Air Force Base at 5 a.m., beginning an 812-mile march honoring their fallen comrades. The Airmen carry 50-pound rucksacks throughout the march, known as the Tim Davis Memorial March, which spans four states and consists of six teams marching relay style 24 hours per day. (U.S. Air Force photo by Staff Sgt. Sharida Jackson)