The 109th Armor Regiment Distinctive Unit Insignia (DUI),
often referred to as a unit crest, was originally approved for the 173rd Tank Battalion on 15 September 1955. It was redesignated in October 1960 after the Battalion became the 109th Armor Regiment, and the insignia was amended to change the symbolism on 309 September 1969.
Yellow and green were frequently used for heraldry of Armor units in the 1940s and 1950s because green was named the sole branch color of Armor from 1947 to 1951; it was switched to yellow after the Cavalry branch was ‘abolished” in 1951. Blue backgrounds inside the two discs represent water and thus recall overseas service; the green areas are allusions to the verdant fields of Europe; in combination with the fleur-de-lis they represent wartime service in France during both World Wars. Yellow areas are a reference to the unit’s service in three Asiatic-Pacific Theater campaigns (one of these includes an Arrowhead device for taking part in an assault landing. “Unleashed Lightning” is the unit motto.
Full guidance on wear of the DUI is found in DA Pamphlet 670-1, Section 21-22, "Distinctive unit insignia" and 21–3(d) and (e), "Beret" and "Garrison Cap," respectively.
♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦
The 109th Armor Regiment was originally constituted in the Tennessee National Guard as a Cavalry Squadron on 30 June 1916 and organized in May 1917 as the 1st Separate Squadron of Cavalry from existing troops. All four of the Squadron’s Troops were called into Federal service (not concurrently) along the Mexican border. On 5 August 1917, the Squadron was drafted into Federal service and converted and redesignated (minus Troop D) as the 114th Machine Gun Battalion, assigned to the 30th Division; Troop D became the 105th Trench Mortar Battery, also assigned to the 30th Division. Before the war’s end, the units would take part in three World War I campaigns (Somme Offensive, Ypres-Lys, Flanders 1918).
Before the Regiment was inducted into Federal service for World War II, it was converted and redesignated as the 181st Field Artillery and relieved of its then-current assignment to the 23rd Cavalry Division. Following a February 1941 induction, the Regiment was broken up and its components underwent several reorganizations and redesignations, too complicated to follow here; the bottom line is that units in the Regimental lineage fought in a total of seven World War II campaigns—four in Europe and three in the Pacific, with one campaign (Ryukyus) in which units took part in an assault landing.
This marked the end of combat deployments for the Regiment and/or its component battalions following the 1943 breakup. Most of its former unit would be reunited and consolidated to form a Regiment, the 109th Armor, in the Combat Arms Regimental System; in 1989, the Regiment was reorganized under the U.S. Army Regimental System.
As of 2019, the Regiment has no active Battalions, but information on when the last Battalion was inactivated is not readily available.