ShieldArgent, on a saltire Azure eight fleurs-de-lis Or.
CrestThat for the regiments and separate battalions of the Maine Army National Guard: From a wreath Argent and Azure, a pine tree Proper.
MottoTO THE LAST MAN.
ShieldThe shield is white, the old Infantry color and alludes to the unit having originally been organized as Infantry. The blue saltire, suggested by the Confederate battle flag, represents service in the Civil War and the fleurs-de-lis refer to service in France, World War I.
CrestThe crest is that of the Maine Army National Guard.
The coat of arms was originally approved for the 103d Infantry Regiment on 22 May 1924. It was redesignated for the 103d Armored Cavalry Regiment on 7 December 1959. It was redesignated for the 20th Armor Regiment on 10 August 1961. The insignia was redesignated for the 133d Engineer Battalion and amended to revise the symbolism on 23 November 1970.