Looks like we are on our third secretary of defense. Acting Secretary of Defense Patrick Shanahan has withdrawn his nomination due to domestic violence problems that apparently included a baseball bat. The current Secretary of the Army, Mark Esper will be nominated for Secretary of Defense. We have a brief bio of him in this post:
The Secretary of Defense has existed since 1947, when James Forrestal became the first. He later committed suicide. There have been 28 men (no women) who have been Secretary of Defense (including 3 acting). Of those, ten served in the U.S. Army: Hagel, Panetta, Perry, Aspin, Weinberger, Clements, Richardson, McNamara (U.S. Army Air Forces), Marshall, Johnson (WWI). Nine have never served in the military (Shanahan, Carter, Cohen, Cheney, Taft, Brown, Schlesinger, McElroy and Wilson).