In the United States Army, the term combat support refers to units that provide fire support and operational assistance to combat elements. Combat support units provide specialized support functions to combat units in the following areas
Combat support should not be confused with combat service support, which are units which primarily provide logistical support by providing supply, maintenance, transportation, health services, and other services required by the soldiers of combat units to continue their missions in combat. Expressed another way, Combat Support units are focused on providing operational support to combat units, while Combat Service Support units are focused on providing logistical support to combat units. Actual combat units are collectively referred to as combat arms units; hence, all army units fall into the category of either combat arms, combat support, or combat service support.[2]
United States Army
Currently, U.S. Army organizational doctrine uses the classification "Maneuver, Fires and Effects" (MFE) and "Operations Support" (OS) to group the former combat support arms branches into Maneuver Support; Special Operations Forces; Network and Space Operations; and Intelligence, Surveillance, and Reconnaissance functional areas.[3]
Within the U.S. Army, the traditional combat support branches are/were:
Chemical Corps (Chemical Warfare Service 1918 / Chemical Corps 1945)
Before the Army ceased using the combat arms / combat support arms / combat service support arms classification system in 2008, the following branches were classified as combat support arms from the year designated. (Note: Army Aviation and Engineers are in fact Combat Arms branches that include Combat Support and Combat Service Support roles.)
Army Aviation (1983) See the Combat Arms – Army Aviation entry for a detailed explanation of the history, organization, and mission of Army Aviation in relation to combat arms / combat support arms classifications.
The Marine Corps does not have a separate "Chemical Corps" but rather mans each GCE battalion with NBC specialist personnel (officer and enlisted) in the battalion operations section. The Marine Corps also maintains a battalion-sized Chemical Biological Incident Response Force (CBIRF) as an element of the II Marine Expeditionary Force (II MEF), responsible for fulfilling the mission of Chemical, Biological, Radiological, Nuclear, and High-Yield Explosive (CBRNE) consequence management.
^U.S. Army Field Manual FM 3-90: Tactics (dated 4 July 2001), Appendix A: Army Branches and Tactical Echelons, Appendix A: Army Branches and Tactical Echelons, A-2, A-13, A-14, A-15, and A-16. Combat Arms, as well as A-8. Combat Support, Figure A-2. Combat Support Capabilities http://www.bits.de/NRANEU/others/amd-us-archive/fm3-90(01).pdf. Retrieved 12 December 2016.