Upon graduation from The Citadel in 1979, LtGen McKenzie was commissioned into the Marine Corps and trained as an infantry officer.
He commanded at the platoon, company, battalion, and Marine Expeditionary Unit (MEU) levels. As a LtCol, he commanded First Battalion, Sixth Marines. As the Commanding Officer of the 22d MEU(SOC), he led the MEU on combat deployments to Afghanistan in 2004 and Iraq in 2005-06.
In the operating forces, his staff assignments included service as an infantry battalion executive officer and as the G-3 Operations Officer of the 2d Marine Division.
His supporting establishment assignments included duty at Marine Barracks Charleston, S.C., and as the Marine Officer Instructor at the Virginia Military Institute.
His headquarters assignments included service as Director of the Commandant’s Staff Group for the 30th Commandant of the Marine Corps, lead action officer for the 2001 QDR effort within HQMC, and the Executive Assistant to the Deputy Commandant for Plans, Policies, and Operations, HQMC. In 2006-07 he served as the Military Secretary to the 33rd and 34th Commandants of the Marine Corps.
In July 2007, upon promotion to BGen, he served on the Joint Staff as a Deputy Director of Operations within the National Military Command Center. In June 2008, he was selected by the Chairman of the Joint Chiefs of Staff to be the Director of the Chairman's New Administration Transition Team (CNATT). In this capacity, he coordinated the efforts of the Joint Staff and the combatant commands in preparing for and executing a wartime transition of administrations. In June 2009, he reported to the International Security Assistance Force (ISAF) in Kabul, Afghanistan, to serve as the Deputy to the Deputy Chief of Staff (DCOS) for Stability. Upon his return from Afghanistan, in July 2010 he was assigned as the Director, Strategy, Plans, and Policy (J-5) for the U.S. Central Command in Tampa, Florida. In August 2012, he reported to Headquarters Marine Corps to serve as the Marine Corps Representative to the Quadrennial Defense Review. In June 2014, he was promoted to LtGen and assumed command of U.S. Marine Corps Forces, Central Command.
LtGen McKenzie is an honors graduate of the Armor Officer Advanced Course, Marine Corps Command and Staff College, and the School of Advanced Warfighting. He has a Masters in Teaching with a concentration in History. He was selected as a CMC Fellow in 1999, and served as a Senior Military Fellow within the Institute for National Strategic Studies at the National Defense University. While there, he wrote the book "The Revenge of the Melians: Asymmetric Threats and the 2001 QDR," published by the National Defense University.
LtGen McKenzie’s awards include the Defense Superior Service Medal, Legion of Merit w/ two gold stars, the Bronze Star, the Defense Meritorious Service Medal, the Meritorious Service Medal w/2 gold stars, the Navy Commendation Medal, and the Combat Action Ribbon. Other awards include the Naval Institute’s Aster Prize for leadership writing, First Place in the Naval Institute’s Marine Corps Essay contest, the Marine Corps’ Association Chase Award for Boldness and Daring, the John A. Lejeune Award from Marine Corps Command and Staff College, the Clifton B. Cates Award from the School of Advanced Warfighting, and the Thomas Jefferson Distinguished Professor Award from the Virginia Military Institute.