Special tactics Airmen, carrying 50-pound rucksacks on a memorial march honoring their fallen comrades, depart Lackland Air Force Base, Texas, Oct. 16, 2011. The 812-mile march, known as the Tim Davis Memorial March, will span across five states and consists of six teams marching relay style 24 hours a day. (U.S. Air Force photo by Staff Sgt. Sharida Jackson)