Deputy Defense Secretary Patrick M. Shanahan and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, lay a wreath during the Centenary of Mateship Commemorative Service at the Washington National Cathedral, Washington, D.C., June 27, 2018. In 2018, Australia and the United States celebrate 100 years of mateship that was first forged in the trenches of World War I during the Battle of Hamel, July 4, 1918. DoD photo by Navy Petty Officer 1st Class Dominique A. Pineiro