Major General Mullen was commissioned in 1986 from Marquette University. As a Lieutenant, he was assigned to 1st Battalion, 3rd Marines in Kaneohe Bay, HI where he served as a rifle and weapons platoon commander, and Battalion training officer.
He then transferred to the Marine Corps Security Force Battalion, Pacific at Mare Island, CA where he served as a platoon commander, executive officer and Commanding Officer of the Fleet Anti-Terrorism Security Team Company. During this period he deployed to Operation Desert Shield and participated in several counter-narcotics missions in support of Joint Task Force-6.
After attending the Advanced Artillery Officer course at Fort Sill, Oklahoma, Captain Mullen was transferred to 2nd Battalion, 4th Marines (later converted to 2nd Battalion, 6th Marines) at Camp Lejeune, NC, and was assigned as the Commanding Officer of Fox Company. He participated in Operation Sea Signal, and deployed with the 26th Marine Expeditionary Unit as the small boat raid and cliff assault company Commander, participating in contingency operations in the former Yugoslavia. He then served as the Inspector-Instructor for Fox Company, 2nd Battalion, 24th Marines in Milwaukee, WI. During this period he led a successful counter- narcotics mission in the Los Padres National Forest of California.
Then Major Mullen was selected to be the Marine Aide to the President and served in that capacity until he was selected to attend the School of Advanced Warfighting. After school, he reported to the Joint Operations Division of the Joint Staff, J-3 for duty in the PACOM and CENTCOM sections and then was selected to serve as the Executive Assistant to the Deputy Director for Regional Operations.
As a Lieutenant Colonel, he reported to the 2nd Marine Division at Camp Lejeune, NC for duty as the Division Plans Officer, then as the Operations Officer for Regimental Combat Team – 8, with whom he deployed to Fallujah, Iraq. Upon returning from deployment he assumed command of 2nd Battalion, 6th Marines and returned to Fallujah, Iraq a year later and was promoted to Colonel. After command he attended the Naval War College at Newport, RI, followed by command of the Marine Corps Tactics and Operations Group at MCAGCC Twentynine Palms, CA.
As a newly promoted Brigadier General, he was assigned as the Commanding General, Education Command and President, Marine Corps University, Quantico, VA. A year later, he was reassigned to the position of Director, Capabilities Development Directorate, Combat Development and Integration. Following his tour in Quantico, Brigadier General Mullen served as the CJOC Director and Target Engagement Authority for fires in support of Iraqi Security Forces during Operation Inherent Resolve. Upon returning to the states, he became the Commanding General, Marine Air Ground Task Force Training Center, MCAGCC Twentynine Palms, CA.
Major General Mullen is currently serving as the Commanding General, Training and Education Command.
Major General Mullen holds a BA and MA in Political Science from Marquette University, as well as an MA in National Security and Strategic Studies from the Naval War College. He is a graduate of the Airborne, Ranger, Summer Mountain Leader and Royal Marine Arctic Warfare Survival courses.