Staff Sgt. Andrew Nichols, a 28th Civil Engineer Explosive Ordnance Disposal team member, performs butterflies during the 50th Anniversary EOD Memorial Day ruck march at Ellsworth Air Force Base, S.D., May 4, 2018. National EOD Memorial Day is designated by Congress as the first Saturday of May in honor of EOD technicians who lost their lives while conducting operations across the globe. (U.S. Air Force photo by Airman 1st Class Nicolas Z. Erwin)