Jeffrey Monssen enlisted and served 30 years active duty in the United Stated Marine Corps and retired as a Sergeant Major.

He deployed to the Western Pacific with the Marine Medium Helicopter Squadron 166 (Reinforced), 13th Marine Expeditionary Unit, aboard the USS Peleliu for 6 months. Upon completion of this deployment, he deployed in support of Operation Desert Shield/Desert Storm with Marine Medium Helicopter Squadron 268 (Reinforced), 5th Marine Expeditionary Brigade, aboard the USS New Orleans for 10 months, upon return he deployed a second time to in support of Operation Desert Storm to support naval vessels within the region for 5 months. In 1992, he deployed to Mogadishu, Somalia with Marine Aircraft Group-16, in support of Operation Restore Hope.

In March 1993, he received his Aerial Observer/Gunner certification in the CH-46E Sea Knight and conducted multiple anti-drug Joint Task Force operations across the United States and South America. In April 1996, he attended Drill Instructor School, MCRD San Diego, California and upon graduation was assigned to Company K, 3d Recruit Training Battalion, Recruit Training Regiment where he served as a Drill Instructor and Senior Drill Instructor.

He then deployed to Kuwait in 2000 with Marine Fighter Attack Squadron 121 in support of Operation Southern Watch. Later that year he reported to 3D Marine Aircraft Wing as an Inspector. Following his selection to Gunnery Sergeant in 2002 he reported to Marine Aviation Weapons and Tactics Squadron 1 in Yuma, AZ.

Following selection to First Sergeant he transferred to Battery G, 2d Battalion, 11th Marines, 1st Marine Division. He deployed 9 months to Fallujah, Iraq in 2006 with Regimental Combat Team 5 in support of Operation Iraqi Freedom. Upon his return, he deployed 8 months on ship with Battalion Landing Team 1/5, 11th Marine Expeditionary Unit in 2008 aboard the USS Tarawa in support of Operation Iraqi Freedom. Upon his return, he reported to School of Infantry East, Marine Combat Training Battalion as a Company First Sergeant. Upon selection to Sergeant Major, reported to School of Infantry East, Infantry Training Battalion.

He then reported to 3d Battalion, 9th Marines, 8th Marines, 2nd Marine Division as the Battalion Sergeant Major and deployed to Helmand Province, Afghanistan, in support of Operation Enduring Freedom in 2012. Upon return, 3d Battalion, 9th Marines was deactivated and he reported to Marine Aircraft Group 31 as the Group Sergeant Major, Beaufort, SC.

In 2015 he assumed his duties as the Training Command Sergeant Major and upon completion of his duties, retired from the United States Marine Corps in 2018.

He and his wife Renee reside in Lakeville, MN continuing to serve veterans, service members, and their families.