Gules, on a pale Or the shoulder sleeve insignia of the 32d Division (a red arrow having shot through a line) Proper, between six fleurs-de-lis of the second.
That for the regiments and separate battalions of the Wisconsin Army National Guard: On a wreath of the colors Or and Gules, a badger couchant Proper.
CATERVAE FERREAE (Of The Brigade Of Iron).
The shield is red for Artillery. The three divisions of the shield produced by the yellow or gold pale charged with a red arrow signify that the organization has been in federal service three times and served as part of the 32d Division during the World War (World War I), the six fleurs-de-lis, three charged on each side of the pale, represent the six engagements in which the regiment participated. The motto indicates that the 121st Field Artillery includes in its personnel a great many descendants of the members of the Iron Brigade of the Civil War.
The crest is that of the Wisconsin Army National Guard.
The coat of arms was originally approved for the 121st Field Artillery Regiment, Wisconsin National Guard on 10 January 1929. It was redesignated for the 121st Field Artillery Battalion, Wisconsin National Guard on 16 January 1952. The insignia was redesignated for the 121st Artillery, Wisconsin Army National Guard on 8 January 1964. It was redesignated for the 121st Field Artillery Regiment, Wisconsin Army National Guard on 11 July 1972.