Brigadier General Sullivan, a native of Huntington, New York, was commissioned a Second Lieutenant on 26 May 1993. Upon graduation from The Basic School and the Infantry Officers Course, he was assigned to 3rd Battalion, 8th Marines in Camp Lejeune, North Carolina. During this tour, he served as a Rifle Platoon Commander, a Weapons Platoon Commander, a Combined Anti-Armor Team Platoon Commander, and Headquarters Company Commander. Deployments during this tour included participation in Operation Deny Flight as a part of 24th Marine Expeditionary Unit; participation in Operation Assured Response in Monrovia, Liberia; operations to guard migrants in Guantanamo Bay, Cuba; and a deployment to Okinawa, Japan.
Brigadier General Sullivan was transferred to The Basic School, Quantico, Virginia, for duty as an instructor in January 1998. He served as a Staff Platoon Commander for three Basic Officer Classes and one Warrant Officer Basic Class. In July 2000, he attended the Command and Control Systems Course.
Brigadier General Sullivan was transferred to 3rd Battalion, 8th Marines in Camp Lejeune, North Carolina in June 2001. During this tour, he served as Lima Company Commander and as the Battalion Executive Officer. In December 2001, as Lima Company Commander, he deployed to Kabul, Afghanistan in support of Operation ENDURING FREEDOM and in December 2002, he deployed to Okinawa, Japan and participated in exercises in the Republic of Korea, the Republic of the Philippines, and mainland Japan.
In September 2003, Brigadier General Sullivan was transferred to the Marine Corps Combat Development Command, Quantico, Virginia, for service as a staff officer in the Concepts and Plans Division. In June 2006, he attended Marine Corps Command and Staff College and in June 2007, he attended the School of Advanced Warfighting. In July 2008, Brigadier General Sullivan reported to the III Marine Expeditionary Force in Okinawa, Japan. He served as a MEF planner and participated in theater security cooperation exercises and engagements throughout the Pacific Command Area of Responsibility, including Thailand, the Philippines, Korea, and Sri Lanka.
In July 2009, Brigadier General Sullivan took command of 3rd Battalion, 8th Marines and joined the 26th Marine Expeditionary Unit as Battalion Landing Team (BLT) 3/8 and deployed in August 2010. BLT 3/8 went ashore into Afghanistan to assume battlespace in the Upper Gereshk Valley. After command, Brigadier General Sullivan attended the Marine Corps War College and spent the 2012-2013 academic year as an instructor at the Marine Corps Command and Staff College. In July 2013, Brigadier General Sullivan assumed duties as a planner in the Joint Staff J-8 focusing on Department of Defense global force management and global posture issues. He took command of 26th Marine Expeditionary Unit in July 2016 and supported Defense Support of Civil Authorities Hurricane Relief Operations in Puerto Rico, the US Virgin Islands, and Key West as well an Amphibious Ready Group/Marine Expeditionary Unit deployment to 6th and 5th Fleets in 2018. From 2018 to 2020, he served as the Chief of Staff of 2nd Marine Division.
In July 2020, Brigadier General Sullivan took command of Naval Amphibious Force, Task Force 51/5th Marine Expeditionary Brigade. In addition to the roles and responsibilities to Naval Forces Central Command and Marine Central Command, he serves as the Commander of a Central Command Joint Task Force capable headquarters. In this capacity, from December 2020 to January 2021, he served as the Joint Force Maritime Component Commander in support of Operation OCTAVE QUARTZ, coordinating the repositioning of U.S. forces in Somalia to other Eastern African operating locations. Most recently, from April to September 2021, he served as the Commanding General of Joint Task Force – Crisis Response aboard Hamid Karzai International Airport, Kabul – in support of Operation ALLIES REFUGE – overseeing the Afghanistan Non-Combatant Evacuation Operation.
On 28 July 2022, Brigadier General Sullivan assumed command of Training Command responsible for officer and enlisted entry-level military occupational specialty, career progression, and career enhancing training to meet force generation and Fleet Marine Force requirements.
Brigadier General Sullivan graduated from the United States Naval Academy in 1993 with a Bachelor of Science Degree in Political Science. He holds Masters Degrees in Military Studies, Operational Studies, and Strategic Studies from Marine Corps University.