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Marine Helicopter Squadron One


Marine Helicopter Squadron One

Headquarters Marine Corps

Quantico, VA
Unit Leaders
HMX-1 Sergeant Major's Biography

Sergeant Major Sean Greenleaf, a native of Oceanside, CA. entered the Marine Corps in November 1992 and was trained as an Infantry Machine Gunner, Infantry Unit Leader, First Sergeant and Sergeant Major.

Throughout his career he has been operationally assigned throughout the MAGTF to include; 3rd Battalion, 5th Marines where he served as a Machine Gunner. 1st Battalion 3rd Marines twice, where he served as a Heavy Machine Gun section leader, Infantry Platoon Sergeant, Company Gunnery Sergeant and Company First Sergeant. Combat Logistic Regiment 17 where he served as a Company 1stSgt, while a member of CLR-17 he deployed as the Sergeant Major with the Redeployment and Retrograde in support of Reset and Reconstitution Operation Group (R4OG). Marine Tiltrotor Squadron 165 where he served as a squadron Sergeant Major and Marine Aerial Refueler Transport Squadron 352 where he served as a squadron Sergeant Major. He has also served as the Sergeant Major of Headquarters and Service Battalion, U.S. Marine Corps Forces, Pacific.

Sergeant Major Greenleaf has been a member of the following training commands; Weapons and Field Training Battalion, MCRD Parris Island where he served as a Primary Marksmanship Instructor. The Basic School at Quantico, VA where he served as a Combat Instructor and deployed to Mosul and Taji Iraq as an advisor to 1st Iraqi Army Division. 3rd Recruit Training Battalion, MCRD San Diego where he served as a Drill Instructor, Senior Drill Instructor and Series Gunnery Sergeant. 

Sergeant Major Greenleaf has deployed several times with the Unit Deployment Program to Okinawa Japan. He has also deployed multiple times in support of Operation Iraqi Freedom, Operation Enduring Freedom and Operation Inherent Resolve.

Sergeant Major Greenleaf is currently serving as the Sergeant Major for Marine Helicopter Squadron One.

His personal awards include the Bronze Star Medal, Meritorious Service Medal and the Joint Service Commendation Medal and Naval Aircrew Insignia.