Lt. Gen. Rex C. McMillian (left), commander of Marine Forces Reserve and Marine Forces North, pins a Vietnam pin onto retired Col. David Leighton to recognize him for his services as a pilot during the Vietnam War at the Lockheed Martin Event Center in Littleton, Colo., Jan. 17, 2017. McMillian attends the executive breakfast to commemorate the 100th anniversary of the Marine Corps Reserve. From World War I through the wars in Iraq and Afghanistan, Reserve Marines have played an essential role in the Marine Corps Total Force by augmenting and reinforcing the active component across the full range of military operations. (U.S. Marine Corps photo by Lance Cpl. Dallas Johnson/Released)