Lt. Col. Shane Lensgraf, 364th Training Squadron commander, leads a group around the track near Lt. Gen. Leo Marquez Boulevard North to kick off the 2018 POW/MIA 24-hour vigil at Sheppard Air Force Base, Texas, Sept. 20, 2018. Retired Air Force Lt. Col. John Yuill, white T-shirt, was a prisoner of war during the Vietnam War for a short period of time when the B-52 Stratofortress he was commanding was shot down over Hanoi, Vietnam. He briefly spoke to a flight of 364th TRS Airmen in training before making the first vigil walk around the track. (U.S. Air Force photo by John Ingle)