National Guardsman Andrew Sullens (left) climbs Half Dome in Yosemite National Park, Calif., with Pat Warren, lead climber from Paradox Sports. Sullens, who lost his leg below the knee while serving in Kapisa province, Afghanistan, participated in the three day climb with other veterans to honor the anniversary of September 11th. David P. Gilkey/NPR hide caption

itoggle caption David P. Gilkey/NPR