Gene Shepherd, a Global Combat Support System-Marine Corps instructor, teaches Marines of the 31st Marine Expeditionary Unit how to use the revolutionary system, May 2. The 31st MEU is the first MEU in the Marine Corps to utilize the system. - Gene Shepherd, a Global Combat Support System-Marine Corps instructor, teaches Marines of the 31st Marine Expeditionary Unit how to use the revolutionary system, May 2. The 31st MEU is the first MEU in the Marine Corps to utilize the system.