Dr. Mark T. Esper, 29th U.S. Secretary of Defense, wrote “A Sacred Oath: Memoirs of a Secretary of Defense During Extraordinary Times” to chronicle his experiences at the Pentagon during the tumultuous term of Donald J. Trump. The pages capture his own life of service in and out of uniform, the old threats, the new Cold War, and the challenges of staying true to your oath. Mark shares his assessment of the country’s current adversaries and his work at West Point’s Modern War Institute and at Red Cell Partners, his VC firm investing in the next generation of tactical and information technology.