Captain O’Sullivan was born 14 March 1989 in Mission Viejo California. He holds a B.S. in Physical Anthropology from the University of California, Santa Barbara (2011). He was commissioned as a 2nd Lieutenant in August 2013 (OCC-R).
Upon Completion of The Basic School and Field Artillery Officer Basic Course, Captain O’Sullivan was assigned to 5th Battalion, 14th Marines (5/14), 4th Marine Division, Naval Weapons Station Seal Beach, California where he served as a Platoon Commander, Fire Direction Officer, and Executive Officer for Oscar Battery.
Captain O’Sullivan assumed command of Headquarters Battery 5/14 in August 2017.