Taking the Oath Defense Secretary James N. Mattis officially swears in Mark T. Esper as the new Secretary of the Army during a ceremony at the Pentagon, Jan. 5, 2018. DoD photo by MC1 Kathryn E. Holm SHARE: Download: Full Size (2.26 MB) Credit: Kathryn E. Holm VIRIN: 180105-D-SH953-0101.JPG Photo Gallery