[7] Coleman joined the United States Navy in April 1968 and was discharged upon his return from Danang, Republic of Vietnam in June 1970.

He attended Amphibious Warfare School during the 1981–82 academic year and was then transferred to HQMC Officer Assignment Branch, and served as a company grade monitor and administrative assistant to the director, Personnel Management Division.

He was promoted to colonel in July 1997 and returned to Camp Lejeune in 1998 for duty with the 2nd Marine Division as the Assistant Chief of Staff, G-4.

In June 2001 he reported to HQMC as the Assistant Deputy Commandant Installations and Logistics (Facilities) and was promoted to brigadier general in November 2002.

He deployed again from February 2004 until June 2004 as commanding general, Combined Joint Task Force Haiti, in support of Operation Secure Tomorrow.

On September 29, 2006, Coleman was assigned as Deputy Commander for Manpower and Reserve Affairs and selected for appointment to the rank of lieutenant general.

At the time, he was only the second African American to attain the rank of lieutenant general in the United States Marine Corps.

[2][8][9] In December 2009, Coleman retired and turned his command of Manpower and Reserve Affairs over to LtGen Richard C. Zilmer.