I Marine Expeditionary Force
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I MEF provides the Marine Corps a globally responsive, expeditionary, and fully scalable Marine Air-Ground Task Force (MAGTF), capable of generating, deploying, and employing ready forces and formations for crisis response, forward presence, major combat operations, and campaigns. 


1st Marine Division
Oct. 6, 2021 | 1:24
1st Marine Division
Oct. 6, 2021 | 1:24
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Photo Information

Lt. Col. Seth E. Anderson (right) passes the 1st Intelligence Battalion’s organizational colors to Lt. Col. B.J. Grass (left) during a change of command ceremony at Camp Pendleton, Calif. June 21, 2017. Grass was the executive officer at the Marine Corps Intelligence schools, Va., and Anderson will attend the U.S. Army War College in Carlisle, Pa. (U.S. Marine Corps photo by Lance Cpl. A. J. Van Fredenberg)

Photo by Lance Cpl. A. J. Van Fredenberg

1st Intelligence Battalion changes command

20 Jul 2017 | I MEF Headquarters Group

1st Intelligence Battalion welcomed a new battalion commander during a change of command ceremony at Camp Pendleton, California, June 21, 2017.

After two years of commanding the battalion, Lt. Col. Seth E. Anderson relinquished command of 1st Intelligence Battalion to Lt. Col. B.J. Grass.

The battalion conducts human and counter intelligence operations, which include data analysis, forensics and battlefield surveillance. I Marine Expeditionary Force Headquarters Group uses these assets both in garrison and while deployed on Special Purpose Marine Air Ground Task Forces and Marine Expeditionary Units.

“We are genuinely excited to have [Grass] here today to command these Marines,” said Col. Roberta Shea, commanding officer, I Marine Expeditionary Force Headquarters Group, who spoke at the ceremony. “Grass has led Marines in missions ranging from combat operations to humanitarian assistance, and we could not have asked for a better officer to lead this battalion.”

Anderson balanced the battalion’s budget of more than $2 million per year while supporting approximately 45 exercises and leading more than 600 Marines. He will move on to Carlisle, Pennsylvania, where he will attend the U.S. Army War College.

“It has been hard and challenging, but it has been fun,” Anderson said. “If the only complaints your Marines have about the battalion is they want to go to war, and they want more opportunities to lead, then you are doing something right.”

Grass has earned three master’s degrees and held billets as a platoon commander, series commander and intelligence officer throughout his 18-year career. He has also deployed to Iraq and Afghanistan and served with the 11th and 15th Marine Expeditionary Units.

Grass was most recently stationed at Marine Corps Intelligence Schools, Virginia Beach, Virginia where he served as the executive officer.

“I am honored and humbled to stand before you today as your battalion commander,” Grass said. “There is no question that this is the greatest personal honor in my professional career. Make no mistake, we will work hard and we will train hard to support the MEF and all of our deployed troops. I look forward to meeting and working with each and every one of you in the days ahead.”

I MEF Leaders

George W. Smith Jr.
Commanding General, I Marine Expeditionary Force

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Brig. Gen. Ryan S. “Chick” Rideout
Deputy Commanding General, I Marine Expeditionary Force

Brigadier General Rideout assumed duties as Deputy Commanding General, I Marine Expeditionary Force in July 2021. His previous assignment was serving as Director, Military Advisor Group, Combined Joint Task Force - Operation INHERENT RESOLVE based in Baghdad, Iraq from June of 2020 to June 2021. Fleet Marine Force assignments include: Commanding

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Colonel Brian Rideout
Chief of Staff, I Marine Expeditionary Force

Colonel Rideout holds a baccalaureate degree in Psychology from Ohio Wesleyan University, a Master of Science in Information Technology Management from the Naval Postgraduate School, a Master of Military Studies from Marine Corps University and a Master of Arts in National Security and Strategic Studies from the Naval War College.  He is a graduate

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Sgt. Maj. Terrence C. Whitcomb
Sergeant Major, I Marine Expeditionary Force

Sergeant Major Whitcomb began Marine Corps Recruit Training on 14 September 1993 at Marine Corps Recruit Depot, San Diego, California with Company C, 1st Recruit Training Battalion.  He was meritoriously promoted to Private First Class and graduated Recruit Training on 10 December 1993. Following graduation from Recruit Training, Private First

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Command Master Chief

 Though a native of Montebello, California, Master Chief Ruiz calls Monte Vista, Colorado home.  He enlisted in the Navy in March 1991, reported to basic training at RTC Great Lakes, Illinois and completed Signalman “A” School at NTC Orlando, Florida.  After serving two tours as a collateral-duty Command Career Counselor in 2000 and 2003, he became

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