Tierced in pairle reversed Gules, Azure and Or; in chief a label of three points Argent. On dexter side an inescutcheon of the second fimbriated, semé-de-lis, overall a saltire all of the last.
On a wreath of the three colors a wyvern without wings sinister couchant reguardant Argent, grasping in its dexter claw a pine tree inverted and eradicated Proper. On its neck a label of three points Azure.
SEMPER IN HOSTES.
The coat of arms was originally approved for the 15th Tank Battalion, part of which was in the old 304th Tank Brigade. Therefore, the shield and crest of the 304th Tank Brigade were used with the label added for difference. The shield is of the colors of the Tank Corps shoulder sleeve insignia. The Brigade was organized at Langres, France, in 1918, so the arms of that place are shown on an inescutcheon differenced by a silver border and by changing the cross from red to silver.
The wyvern is from the original insignia of the French Tank Corps. The uprooted pine tree commemorates the activities of this Brigade in the Argonne forest during the Meuse-Argonne operations.
The coat of arms was originally approved for the 15th Tank Battalion on 12 July 1921. It was reassigned to the 1st Tank Regiment on 10 July 1930 and further reassigned to the 66th Infantry (Light Tanks) on 17 November 1932. The insignia was redesignated for the 66th Armored Regiment on 25 April 1942. It was redesignated for the 66th Medium Tank Battalion of 27 December 1950. The insignia was redesignated for the 66th Armor Regiment on 26 September 1958.