Sergeant Major Leavy enlisted in the Marine Corps on 21 May 1996 and underwent recruit training at Parris Island, South Carolina. He Graduated recruit training on 13 August 1996. He then reported to The School of Infantry for Marine Corps Combat Training in Camp Lejeune, North Carolina. Upon Completion of MCT, he remained at Camp Lejeune where he attended the Financial Management School. Upon Completion of MOS School, he was transferred to Marine Corps Security Force Battalion, Norfolk VA where he served as a disbursing clerk.
In December of 2000, he was transferred to Headquarters Battalion, MCB Okinawa where he served as the NCOIC for the Pay Section. In April 2001, he was hand selected to serve as the Chief of Staff Personal Assistant and Primary Driver. In January 2002, he transferred to III Marine Expeditionary Force, where he served as the NCOIC for the Operations Section. During his tour with III MEF he participated in numerous deployments and operations, to include a combat tour in the Philippines 2002. In January 2003, Sergeant Leavy was hand selected to instruct the Corporal's Course. In December of 2003, he attended Drill Instructor School followed by Close Combat Instructor Course.
Sergeant Leavy was then assigned to 2d Recruit Training Battalion as a Drill Instructor. He served as a Drill Instructor and Senior Drill Instructor from May 2004 to February 2006. During his period, Staff Sergeant Leavy was selected for a summer cycle at Officer Candidate School, where he served as a Sergeant Instructor for a senior company, during the summer of 2005. In February of 2006 he was assigned to Instructional Training Company, Support Battalion where he served as a Martial Arts Instructor. In September 2006, he graduated the Close Combat Instructor Trainer Course and returned to the Martial Arts Section until the completion of his tour in February of 2007.
In April 2007, he reported to Headquarters and Service Battalion, Quantico Va and was assigned to the Base Disbursing Office as the SNCOIC of the travel section. In August of 2007, Staff Sergeant Leavy was assigned to Headquarters Company as the Company GySgt. In January 2008, he returned to the Base Disbursing Office as the SNCOIC of the separations sections. In April 2008, Staff Sergeant Leavy was assigned to Officer Candidate School, where again he served as a Sergeant Instructor for Echo Company during the summer of 2008. In September 2008, he reported to Service Company, Combat Logistics Regiment 17, 1st Marine Logistics Group. He was assigned to I MEF Finance Office as the SNCOIC of the production pay section. In June 2009, Gunnery Sergeant Leavy was assigned to Headquarters Company as the Company GySgt. In March 2010, Gunnery Sergeant Leavy deployed to Afghanistan with Headquarters and Service Company, 1st MLG (10-1) as the Operations Chief and SNCOIC of the Corporal's Course. In March 2011, Sergeant Major Leavy returned from deployment and was assigned back to Service Company, CLR-17, 1st MLG working at the Finance Office as the SNCOIC for the production travel section.
In August 2012, Gunnery Sergeant Leavy was assigned to Service Company as the Company 1stSgt. In Feb 2013 he was frocked to the rank of First Sergeant and was transferred to 3d Law Enforcement Battalion, III MEF Headquarters Group, and was assigned as the First Sergeant for Alpha Company. In March 2014, First Sergeant Leavy was reassigned to Headquarters and Support Company, currently serving as H&S Company 1stSgt. In May 2016, First Sergeant Leavy was assigned to Fox Company, 2d Recruit Training Battalion as the Company 1stSgt. In April 2017 he was frocked to the rank of Sergeant Major and was transferred to 3d Recruit Training Battalion MCRD PISC. In November 2018 SgtMaj Leavy was transferred to Marine Medium Tilt Rotor Squadron 161. In September 2019, he deployed with the squadron to Kuwait as part of the Special Purpose Marine Air Ground Task Force-Crisis Response-Central Command 20.1 and returned June 2020.
SgtMaj Leavy's personal declarations include the Meritorious Service Medal (second award), Navy and Marine Corps Commendation Medal, and the Navy and Marine Corps Achievement Medal (of fourth award).