Under Operation Switchback in 1963, various programs intially
operated by the Central Intelligence Agency were handed over to
Military Assistance Command Vietnam (MACV).  Perhaps most notable had
been the Civilian Irregular Defense Group (CIDG Program).
MACV was intent on creating action elements out of these essentially
defense oriented arms, including the Mobile Guerrilla Force.
*
The Mobile Guerrilla Force (MGF) was first created at the end of 1966,
and was designed to provide stand-alone action elements for the US
establish Corp Tactical Zones (CTZs), as opposed to the more localized
Mobile Strike Forces (MSF or MIKE Force).  As a result, the MGF had
an integrated recon platoon in order to provide better scouting
capability.  The MGFs were systematically absorbed into the MSFs
starting during 1967, with all MGFs becoming MSFs by the end of 1968.
*
Organizations provided here are approximations based on
available evidence.