Brigadier General Sullivan 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 CAAT Platoon Commander, and H&S Company Commander. Deployments included participation in Operation Deny Flight as a part of 24th Marine Expeditionary Unit (SOC); 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 and 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 (CCSC).
Brigadier General Sullivan was transferred to 3d 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 Cops Command and Staff College and in June 2007, he attended the School of Advanced Warfighting. In July 2008, he 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 PACOM AOR 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 MEU as 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 he 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 MEU in July 2016 and supporting DSCA Hurricane Relief Operations in Puerto Rico, the US Virgin Islands, and Key West as well an ARG/MEU deployment to 6th and 5th Fleets in 2018. He assumed the responsibilities of Chief of Staff of 2nd Marine Division from 2018 to 2020.
In July 2020, Brigadier General Sullivan took command of Naval Amphibious Force, Task Force 51/5th Marine Expeditionary Brigade, the first command structure of its kind since World War II, where NAVCENT and MARCENT signed a MOU to integrate U.S Navy and U.S Marine Corps forces under one structure that can prosecute a single battle concept, strengthen partnership with both Naval and special operations forces, and enhance crisis response operations for Commander, USCENTCOM.
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. Brigadier General Sullivan is married to Marta Sullivan and they have four sons: Peter (14), Daniel (12), Brendan (9), Joseph (8). He is from Huntington, New York.