ShieldArgent, perched upon an Infantry bayonet fessways Azure a cardinal bird rising, wings elevated and addorsed Gules.
CrestThat for the regiments and separate battalions of the Army Reserve: On a wreath of the colors Argent and Gules the Lexington Minute Man Proper. The statue of the Minute Man, Captain John Parker (H.H. Kitson, sculptor), stands on the common in Lexington, Massachusetts.
MottoUNITED WE STAND.
ShieldThe shield is white, or silver, which was the old Infantry color, charged with an Infantry bayonet in blue, the present Infantry color, upon which is perched a cardinal, a songbird representative of the citizen soldier who loves peace but when aroused will take arms for war.
CrestThe crest was that of the United States Army Reserve.
The coat of arms was originally approved for the 400th Infantry Regiment on 12 May 1926. It was redesignated for the 400th Regiment on 1 February 1960.