Master Gunnery Sergeant Robert L. Trenum is originally from Westernport, MD. He graduated from Westmar High School in 1995 and enlisted in the Marine Corps on September 19, 1995. Upon completion of recruit training at Marine Corps Recruit Depot, Parris Island, SC, he attended the Basic Course of instruction at the Armed Forces School of Music in Norfolk, VA.
His first fleet assignment was as a percussionist with the Marine Corps Air Ground Combat Center Band, Twentynine Palms, CA. There, he served as Administration Chief, Percussion Section Leader, Fire Team Leader, and Squad Leader. While at Twentynine Palms, LCpl Trenum was promoted to the rank of Corporal on December 1,1996 and Sergeant on June 1,1998.
In September of 1999, upon completion of his tour at Twentynine Palms, Sergeant Trenum was assigned to Drill Instructor School at Marine Corps Recruit Depot, San Diego, CA. After graduating from Drill Instructor School, he was assigned to First Recruit Training Battalion, Alpha Company. There, he served as a Drill Instructor and as a Senior Drill Instructor. He was later reassigned to Headquarters Company, First Recruit Training Battalion as the Battalion S-4 Chief and S-4 Officer. On January 1, 2002, Sgt Trenum was promoted to the rank of Staff Sergeant. 
In September of 2003, SSgt Trenum detached from the First Recruit Training Battalion and reported to the First Marine Division Band. SSgt Trenum’s assignments within the Division Band have included Percussion Section Leader, Rhythm Section Commander, Martial Arts Instructor, Training Chief, Supply Chief, and Assistant Instrument Repair Technician. In 2004, while deployed with the First Marine Division Band in support of Operation Iraqi Freedom, SSgt Trenum served as Commander of the Guard, Sergeant of the Guard, Vehicle Commander, and Training SNCOIC. Following his deployment, he was assigned as the Acting Instrument Repair Technician and Supply SNCOIC for the Division Band. 
In February 2007, SSgt Trenum was selected for a lateral move to Instrument Repair Technician and attended Minnesota State College Southeast at Red Wing, MN for training. He was promoted to Gunnery Sergeant on August 1, 2007. In May 2008, he graduated from Minnesota State College, Red Wing and in July 2008, GySgt Trenum reported to the Marine Corps Air Ground Combat Center Band to serve as the unit’s Instrument Repair Technician. In July 2010, GySgt Trenum transferred to Cherry Point, North Carolina, where he served as the 2d Marine Aircraft Wing Band’s Instrument Repair Technician. 
In 2013, GySgt Trenum transferred to the Marine Detachment, Naval School of Music in Norfolk, VA to serve as the Head Instrument Repair Technician for the field. He was promoted to the rank of Master Sergeant in February 2014. In October 2018 he was promoted to his current rank and in April 2019, assigned as the Senior Enlisted Advisor for the Marine Detachment, Little Creek. In January 2021, MGySgt Trenum reported to the Marine Corps Forces Pacific Band, Kaneohe Bay, Hawaii to serve as the Enlister Band Leader and Instrument Repair Technician.
His military decorations include the Meritorious Service Medal, the Navy and Marine Corps Commendation Medal (3rd Award), the Navy and Marine Corps Achievement Medal (2nd Award), the Navy Unit Commendation (2nd Award), the Navy Meritorious Unit Commendation (2nd Award), the Marine Corps Good Conduct Medal (9th Award), the National Defense Service Medal (2nd Award), the Iraqi Campaign Medal (2nd Award), the Global War on Terrorism Service Medal, the Sea Service Deployment Ribbon, and the Marine Corps Drill Instructor Ribbon.