Originally from Raymond, Maine, SgtMaj. Mancini graduated from MCRD Parris Island in December 1995. Following completion of MCT he completed the KC-130 Communication/Navigation/Identification Course at MCAS Cherry Point, North Carolina and reported to Marine Transport Squadron One (VMR-1), Cherry Point, North Carolina for duty as an Avionics Technician and, subsequently, a Crew Chief on the C-9B.
While attached to VMR-1, SgtMaj. Mancini served as a Quality Assurance Representative for Avionics and Power Plants for the C-9B. As a Crew Chief, he accumulated over 1680 hours and was the Commanding Officer's choice for high visibility missions. During his tour, he also served on the squadron color guard, participating in several community and squadron events.
In October 2002, SgtMaj. Mancini reported to Basic Recruiter School, MCRD San Diego, California. Upon graduation, he reported to Recruiting Station (RS) Louisville, Kentucky and was assigned as a Canvassing Recruiter at Recruiting Sub-Station (RSS)
Evansville, Indiana, Permanent Contact Station (PCS) Owensboro, Kentucky, where he also served as the Assistant SNCOIC. In FY 2005, RSS Evansville was awarded RSS of the Year.
In August 2006, SgtMaj. Mancini reported to Marine Aerial Refueler Transport Squadron 252, MCAS Cherry Point, North Carolina, where he served as the Comm/Nav SNCOIC and Quality Assurance SNCOIC/Chief. During this period, SgtMaj. Mancini deployed twice to Al Asad, Iraq, in support of Operation Iraqi Freedom.
In June 2010, SgtMaj. Mancini reported to the Center for Naval Aviation Technical Training Detachment Little Rock, Arkansas, as a KC-130J Comm/Nav SNCOIC/Instructor and served as an Instructor Evaluator, Course Supervisor, and Squadron Gunnery Sergeant.
In December 2013, SgtMaj. Mancini reported to Marine Aerial Refueler Transport Squadron 152, MCAS Futenma, Okinawa, Japan, and was assigned as the SNCOIC of Maintenance Control. In July 2014, SgtMaj. Mancini played a key role in permanently moving the entire squadron to Iwakuni, Japan, ensuring there was no operational pause.
In February 2016, SgtMaj. Mancini reported to 1st Battalion, 12th Marines, 3rd Marine Division, MCBH Kaneohe Bay, Hawaii, where he served as the Battery A First Sergeant. During this period, SgtMaj. Mancini completed one deployment to Okinawa, Japan. In February 2018, SgtMaj. Mancini was one of three Marine First Sergeants selected to attend the United States Army Sergeant's Major Academy (USASMA).
In June 2018, SgtMaj. Mancini reported to the USASMA, Ft Bliss, Texas, where he served as a student, and was the first Marine to obtain a Bachelor of Arts degree in Leadership and Workforce Development from The Army Command and General Staff College. Upon graduation in June 2019, he reported to Combat Logistics Battalion 2, Camp Lejeune, North Carolina, where he served as the Transportation Services Company First Sergeant and Battalion Sergeant Major.
In August 2020, SgtMaj. Mancini was promoted to his current rank and reported to 2D Landing Support Battalion as the Battalion Sergeant Major until January 2021.
From January 2021 to October 2023, SgtMaj. Mancini assumed the duties as the Battalion Sergeant Major for 8th Engineer Support Battalion.
On Oct. 27, 2023, SgtMaj. Mancini assumed the duties of station Sergeant Major for MCAS New River in Jacksonville, North Carolina.
SgtMaj. Mancini's personal decorations include the Navy and Marine Corps Commendation Medal w/3 gold stars, Navy and Marine Corps Achievement Medal w/1 gold star, and the Military Outstanding Volunteer Service Medal.