Shield
Crimson, in front of a dexter arm embowed couped, grasping a double-end wrench Or, a sword erect, blade Sable, hilt of the second, that portion behind the arm fimbriated of the last.
Crest
From a wreath Or and Crimson, a wavy annulet Celeste (Light Blue), overall three swords, two in saltire and one palewise, points upward, blades, hand guard and pommel of the first, grip Gules, surmounted by a stylized eagle displayed Sable, beak and legs of the first, langued and talons of the fourth bearing on its chest a fleur-de-lis of the first.
Motto
SERVICE BEHIND THE SWORD.
Shield
The crimson and yellow are the colors of the Ordnance Department which was the original designation of the unit. The maintenance functions of the battalion are symbolized by the strong right arm of the personnel holding the double-end wrench, a tool frequently used in the performance of duties. The martial aspect is indicated by the upright sword. The motto, "Service Behind The Sword," alludes to the symbolism of the shield and to the manner of service rendered.
Crest
Blue denotes commitment. Black symbolizes solidarity. The following images indicate the campaign history of the Battalion during World War II in Europe: the eagle, traditionally used in European heraldry, recalls wartime service in Central Europe, Ardennes-Alsace and Germany; the wavy annulet suggests water or a river and refers to action in the Rhineland; and the fleur-de-lis signifies Normandy and Northern France. The colors of the three swords illustrate action in multiple military operations - Vietnam, Southwest Asia and Iraq, in which the unit was awarded the Meritorious Unit Commendation streamer.
The coat of arms was originally approved for the 185th Ordnance Heavy Maintenance Battalion on 4 February 1943. It was rescinded on 7 January 1955. The insignia was reinstated and redesignated for the 209th Support Battalion and amended to include a crest on 30 April 2012.