Central Command, or CENTCOM, is an administrative unit of the US Armed Forces that is in charge of all military movement and strategy in the Middle East. Mattis was put in charge of CENTCOM by President Obama in 2010.

Joint Forces Command, or JFCOM, was an administrative command unit much like CENTCOM, designed to provide services to the Armed Forces. Mattis was given command of JFCOM in 2007 but disbanded the agency in 2010, feeling that it added little value to realizing the objectives of the Armed Forces.

A fighting unit of roughly 500 to 1,000 men with its own headquarters. When Mattis was promoted to Lieutenant Colonel, he was given charge of the 1st Battalion of the 7th Marine Regiment. This was the battalion he led in the Gulf War.