Northeast quadrant of a U.S. military topographic map covering the Nam Ngo river valley in Laos, part of the reference materials associated with the 'Boxer 22' combat search-and-rescue operation during the Vietnam War. The marked fuel pipeline and mountain terrain illustrate the difficult, heavily defended landscape that rescue aircrews had to navigate in their efforts to recover downed American airmen along the Ho Chi Minh Trail. Project: 218834