Is the 72nd field brigade part of the oldest or newest established field army?
72nd Field Artillery Brigade (United States) The 72nd Field Artillery Brigade is an AC/RC unit based at Joint Base McGuire-Dix-Lakehurst, New Jersey. The unit is responsible for training selected United States Army Reserve and National Guard units along the East coast. The brigade is a subordinate unit of First Army Division East, First United States Army.
111th Sustainment Brigade (United States) The 111th Sustainment Brigade started out as the 111th Air Defense Artillery Brigade of the United States Army. On 1 February 2008, this New Mexico National Guard Army unit ceased its air defense mission and was reorganized and redesignated as a maneuver enhancement brigade. Similar to a special troops battalion, its mission was to support units of the Regular Army. On the 1st of September 2016, the brigade was redesignated, once again, as a sustainment brigade that focuses on providing mission command for combat support and combat service support units. The brigade is designed to operate independently in a theater of operations, in conjunction with other sustainment brigades under the command of a sustainment command (expeditionary), or directly under a theater sustainment command.