Sergeant Major Cornell S. Cornish enlisted in the Marine Corps on 16 October 2001 attending Recruit Training at MCRD Parris Island, South Carolina. Upon graduation from boot camp, Private First Class Cornish reported to Marine Combat Training at Camp Lejeune, NC. In May 2002, he reported to Engineer Equipment Instruction Company in Fort Leonard Wood, MI where he attained the MOS of 1345/ Engineer Equipment Operator.
In August 2002, Private First Class Cornish reported to his first duty station at Marine Wing Support Squadron 171, Marine Corps Air Station, Iwakuni, Japan. During this period, he was assigned to the Engineer Company and served as an Engineer Equipment Operator, and Marine Corps Integrated Maintenance Management System clerk. While serving with Marine Wing Support Squadron 171, Lance Corporal Cornish participated in exercise Foal Eagle.
In July 2004, Corporal Cornish reported to Marine Wing Support Squadron 372, Camp Pendleton, California. He was assigned to Engineer Company serving as the Engineer Equipment Operator completing one deployment in support of Operation Iraqi Freedom II and a second in support of Operation Iraqi Freedom 5-7. He was later promoted to the rank of Sergeant June 2005.
In July 2006, Sergeant Cornish reported to Combat Logistics Battalion 15, Camp Pendleton, California. He was assigned to Engineer Detachment serving as the Engineer Detachment Platoon Sergeant. On April 2008 Sergeant Cornish was meritoriously promoted to the rank of Staff Sergeant later deploying with the 15th Marine Expeditionary Unit in support of WESTPAC 08-02.
From January 2009 to June 2010, he served as Engineer Equipment Chief, Combat Logistics Battalion 5, Motor Transportation Company, Heavy Equipment Platoon. He was subsequently transferred to Combat Logistics Battalion 4, Okinawa, Japan and deployed to Afghanistan in February 2012.
In October 2012, Staff Sergeant Cornish reported to Drill Instructor School, Class 1-13, MCRD San Diego and was assigned to Company I, 3d Recruit Training Battalion where he served as Drill Instructor and Chief Drill Instructor. During his tenure, he was temporarily transferred to Support Battalion where he served as the Receiving Company Gunnery Sergeant and Company First Sergeant. He was promoted to Gunnery Sergeant in September 2013.
Upon completion of Drill Instructor Duty in December 2015, Gunnery Sergeant Cornish reported to 1st Maintenance Battalion, 1st Marine Logistics Group. Throughout his time in the battalion, he served as the Engineer Equipment Chief and Company First Sergeant for Engineer Maintenance Company.
In January 2017, Gunnery Sergeant Cornish reported to I Marine Expeditionary Force, G7, Expeditionary Operations Group and served as the Exercise Operations Chief for a period of twelve months before being selected to the rank of First Sergeant.
In March 2018 First Sergeant Cornish reported to 3d Battalion, 4th Marines, Twentynine Palms, California for duty as First Sergeant, Company L where he deployed in support of Operation Freedom Sentinel Afghanistan. In May 2019, he was selected to serve as First Sergeant, Weapons Company where he subsequently participated in the Southwest Border Mission, El Centro California.
In Mar 2020, he reported to Marine Corps Recruit Depot San Diego, California for duty as Company First Sergeant, Company G, 2d Recruit Training Battalion. Also while assigned at MCRD he assumed the duties as the Battalion Sergeant Major, 2d Recruit Training Battalion, and Company First Sergeant Instructional Training Company, Support Battalion, Recruit Training Regiment.
In January 2022 Sergeant Major Cornish was promoted to his current rank and was transferred to assume his current assignment as Battalion Sergeant Major, 3rd Battalion, 5th Marines, Camp Pendleton California.
Sergeant Major Cornish is a graduate of the Sergeant Course, Career Course, Advanced course, First Sergeant Course and USMC Senior Enlisted Professional Military Education Course. He is also an alumni of Trident University where he completed an Associate of Science degree in professional studies.
Sergeant Major Cornish’s personal decorations include the Navy and Marine Corps Commendation Medal (with Combat C and two gold stars in lieu of third award), Navy and Marine Corps Achievement Medal (gold star in lieu of second award), Combat Action Ribbon, and Good Conduct Medal (bronze star in lieu of 5th award).