Mark Thomas Esper was born on April 26, 1964, in Uniontown, Pennsylvania. He attended the United States Military Academy, graduating with a Bachelor of Science in engineering in 1986. He later earned a Master of Public Administration from Harvard’s John F. Kennedy School of Government in 1995 and a Ph.D. in Public Policy from George Washington University in 2008.

After graduating from West Point, Esper joined the US Army and served in the 101^st Airborne Division during the Persian Gulf War from 1990 to 1991. After ten years in the Army, he transitioned to the Army National Guard and the Army Reserve. He retired from the US Army in 2007 with the rank of lieutenant colonel.

From 1996 to 1998, Esper was chief of staff at The Heritage Foundation, a conservative think tank in Washington, DC. He then took a variety of positions within the federal government: he worked as a senior policy advisor for Senator Chuck Hagel, a professional staff member for the Senate Foreign Relations and Government Affairs committees, and national security advisor for Senate Majority Leader Bill Frist. During the George W. Bush administration, Esper was deputy assistant Secretary of Defense for negotiations policy from 2002 to 2004.

Moving to the private sector, Esper was a vice president at Aerospace Industries Association from 2006 to 2007, and a senior executive at Raytheon Company, a defense contractor, from 2010 to 2017. In 2017, he became the Secretary of the Army. He held that position until President Donald Trump nominated him to become the 27th Secretary of Defense in 2019. He was sworn in as secretary on July 23, 2019.