The 117th Regiment Distinctive Unit Insignia—commonly called a unit crest or DUI for short—was originally approved for the 117th Infantry Regiment, Tennessee National Guard on 5 June 1934. It was redesignated on 28 July 1955 for the 117th Armored Infantry Battalion, Tennessee National Guard; on 11 October 1960 for the 117th Infantry Regiment, Tennessee National Guard; and on 15 April 1997 for the 117th Regiment, Tennessee Army National Guard.
A blue shield is used to commemorate the service of the unit when it was designated as an Infantry Regiment. A chevron rompu (broken) in the center evokes the image of breaking through enemy lines and is in tribute to the “Break Through” of the Hindenburg Line during World War I. Three mullets (five-pointed stars) represent the three battle honors the Regiment was awarded for World War I.
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.
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Until it was passed along to the 278th Armored Cavalry Regiment, the nickname of the 117th Infantry Regiment/117th Regiment was the Third "Tennessee,” a tribute to the original designation of the parent unit constituted on 25 March 1887 as the 3rd Infantry Regiment, Tennessee National Guard. Though mustered into Federal service on several occasions, the Regiment did not serve outside the continent U.S. until World War I, when was reorganized and redesignated as the 117th Infantry Regiment and assigned to the 30th Division. It would fight in three World War I campaigns as part of the 30th and help smash through Hindenburg Line in its first full breach of the war.
During World War II, the 117th Infantry Regiment retained its designation and its affiliation with the 30th Division. Fighting in five campaigns in Europe, the Regiment earned two Presidential Unit Citations, a French Croix de Guerre with Silver Star, and a Belgian Fourragere for two citations in the Order of the Day of the Belgian Army.
Following the war, the Regiment was broken up and its HQ and 1st Battalion redesignated as the 117th Armored Infantry Battalion. In March 1959, it was consolidated with the 170th Armored Infantry Battalion and the 278th Armored Infantry Battalion, the 330th Antiaircraft Artillery Battalion, and the 176th Tank Battalion to form a reorganized and redesignated 117th Infantry Regiment comprising four battalions (1st through 4th), all elements of the 30th Armored Division. The Regiment’s organization was reduced to the 2nd, 3rd, and 4th battalions in November 1973, and 1997 it was redesignated for the final time as the 117th Regiment.
As of Summer 2023, the 1st, 2nd, and 3rd Battalions of the 177th Regiment are assigned to the Tennessee Army National Guard's 117th Regional Training Institute, where they conduct training in the Military Police, Armor, and Quartermaster branches, respectively.