Mattis Remarks Defense Secretary James N. Mattis formally swears in the Secretary of the Army Dr. Mark Esper at the Pentagon, Jan. 5, 2018. DoD photo by MC1 Kathryn E. Holm SHARE: Download: Full Size (1.02 MB) Credit: Kathryn E. Holm VIRIN: 180105-D-SH953-0080.JPG Photo Gallery