In 1955 then Captain Gray was tasked with forming two units, one to be assigned to Europe and the other to the Pacific area,[8] chosen from Marines undergoing Manual Morse intercept training at the Naval Security Group (NSG) training facility at Imperial Beach, California.

Upon completion of the course at Imperial Beach, the Pacific team under his command reported for duty with the NSG at Kamiseya, Japan in May 1956.

In 1958 then-Captain Gray was assigned to Hawaii to form and activate the 1st Radio Company, a tactical signals intelligence (SIGINT) unit, where he would serve from September 1958 to May 1961.

MajGen Dimitri Henry served as the Commanding Officer, Co H, Marine Cryptologic Support Battalion, San Antonio, TX, from 2001–2004.

He has since served as a Defense Intelligence Senior Executive Service (DISES) executive at Headquarters U.S. Marine Corps (HQMC)as the Assistant Director of Marine Corps Intelligence and then at the National Security Agency (NSA) from October 2017 – present.