Sergeant Major Thomas Yeaman enlisted in the Marine Corps in 2003 and completed recruit training at Marine Corps Recruit Depot San Diego, CA. Private Yeaman then reported to Marine Combat Training (MCT) at the School of Infantry, Camp Pendleton, CA. Upon completion of MCT, he reported to Aviation Maintenance Squadron 2, Marine Aviation Training Support Group 23 at Naval Air Station Pensacola, FL for Military Occupational Specialty (MOS) training. Private First Class Yeaman completed Aviation Intermediate Level Training, and then reported to Naval Air Maintenance Training Detachment at Miramar, CA where he completed Consolidated Automated Support System MOS Training (6467).
 
Upon completion of MOS training, Lance Corporal Yeaman reported to Marine Aircraft Group 11, Marine Aviation Logistics Squadron 11 Miramar, CA where he served as an Intermediate Level Technician. In January of 2006, Corporal Yeaman deployed with Marine Fighter Attack Squadron 314 as a Collateral Duty Inspector to Iwakuni, Japan. While deployed Corporal Yeaman attended the Corporal's Course Leadership Class where he graduated as the Class Iron Man and won the Noncommissioned Officer of the Third Quarter. 
 
In June of 2008, Sergeant Yeaman reported to Drill Instructor School at Marine Corps Recruit Depot San Diego, CA. Upon completion of Drill Instructor School, Sergeant Yeaman was assigned the MOS of Drill Instructor (0911), and was assigned to Recruit Training Regiment, 3rd Battalion, Lima Company. While assigned to Lima Company Sergeant Yeaman held the billet of Drill Instructor, Senior Drill Instructor, and Chief Drill Instructor.   
 
In March of 2012, Staff Sergeant Yeaman reported to Marine Aircraft Group 13, Marine Aviation Logistics Squadron 13 in Yuma, AZ. He was assigned as the Reconfigurable Transportable Consolidated Automated Support System (RTCASS) Work Center Supervisor and Collateral Duty Inspector. In August of 2013 Staff Sergeant Yeaman deployed with Marine Attack Squadron 214 on the 13th Marine Expeditionary Unit where he served as the Marine Aviation Logistic Squadron Detachment SNCOIC and Production Control Chief. 
 
In August of 2015, Staff Sergeant Yeaman reported to Aviation Maintenance Squadron 2, Marine Aviation Training Support Group 23, Naval Air Station Pensacola, FL for duty as an Aviation Electrician's (AE) Mate Instructor. In August of 2016 Staff Sergeant Yeaman was promoted to the rank of Gunnery Sergeant and assumed the responsibilities as the AE Course Lead Instructor.
 
In December of 2017, Gunnery Sergeant Yeaman was selected to be the Assistant Marine Officer Instructor (AMOI) for the University of Nebraska-Lincoln. Gunnery Sergeant Yeaman augmented Officer Candidate School (OCS) during the summers of 2018, 2019 as a Sergeant Instructor. In April of 2020 he was frocked to the rank of First Sergeant and returned to OCS during the summer of 2020 where he served as the India Company First Sergeant.
 
In December of 2020, First Sergeant Yeaman reported to Combat Logistics Battalion 4, where he served as the Motor Transportation Company and Headquarters and Service Company First Sergeant. In December of 2021, First Sergeant Yeaman participated in Resolute Dragon 21 aboard the Combined Arms Training Center Camp Fuji in Shizuoka Prefecture, Japan as the Senior Enlisted Advisor for Combat Logistics Detachment 343.
 
In March of 2022, First Sergeant Yeaman reported to Combat Logistics Regiment 37, where he served as the Headquarters Company First Sergeant. In January of 2024, he participated in Korean Marine Exchange Program 24.1 as the Senior Enlisted Advisor for Combat Logistics Detachment 371. In April of 2024 he was frocked to the rank of Sergeant Major.
 
In April of 2024, Sergeant Major Yeaman reported to Marine Fighter Attack Squadron 214 were he currently serves as the Squadron Command Senior Enlisted Leader. 
  
Sergeant Major Yeaman's personal awards include the Meritorious Service Medal, Navy Commendation Medal w/ two gold stars in lieu of third award, and the Navy and Marine Corps Achievement Medal.