The 1st Battalion, 121st Field Artillery is currently part of the 157th Maneuver Enhancement Brigade that is based out of Milwaukee, Wisconsin. Attached to the 1-121st is Battery A located in Hartford, Wisconsin; Battery B located in Plymouth, Wisconsin; 108th Forward Support Company located in Sussex, Wisconsin.

The 157th Maneuver Enhancement Brigade, also known as the Iron Brigade, is based out of Milwaukee, Wisconsin. It was formerly known as the 57th Field Artillery Brigade, at which time its subordinate organizations included the 1st Battalion, 126th Field Artillery Regiment and the 1st Battalion, 121st Field Artillery Regiment from the Wisconsin Army National Guard, plus the 1st Battalion, 182nd Field Artillery Regiment of the Michigan Army National Guard. Not to be confused with the famous "Iron Brigade" of the Civil War, its nickname was traditionally given to crack artillery units in the Civil War. It was during World War I that the 57th Field Artillery Brigade earned its nickname as it spent many hours at the front and fired more artillery rounds than any brigade in the American Army.