The 129th Field Artillery Regiment is a regiment of the Field Artillery Branch of the United States Army, part of the Missouri Army National Guard. The 1st Battalion is the only active unit of the regiment, with the battalion Headquarters and Headquarters Battery in Maryville, Battery A in Albany, Battery B in Chillicothe, and Battery D in Independence. The battalion is a subordinate unit of the 130th Field Artillery Brigade, headquartered in Manhattan, Kansas.

The Army National Guard (ARNG), in conjunction with the Air National Guard, is an organized militia force and a federal military reserve force of the United States Army. They are simultaneously part of two different organizations: the ARNG of each state, most territories, and the District of Columbia, as well as the federal ARNG, as part of the National Guard as a whole. It is divided into subordinate units stationed in each state or insular area, responsible to their respective governors or other head-of-government.