Also known as a unit crest or DUI, a Distinctive Unit Insignia is worn by all Soldiers (except General Officers) in units that have been authorized to be issued the device. It is worn centered on the shoulder loops of the Army Green Service Uniform (AGSU) and the blue Army Service Uniform (ASU, Enlisted only) with the base of the insignia toward the outside shoulder seam. 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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The 51st Infantry Regiment Distinctive Unit Insignia was originally approved for the 51st Regiment Infantry on 24 January 1930 and was amended on 11 May 1937. To give you an idea of how many times the Regiment and its units underwent redesignations and other changes, the insignia was subsequently redesignated six times—and that is two fewer times than the remaining active unit, Company F, was redesignated. The shield of the insignia is blue for infantry, and the gold bend is taken from the arms of Alsace. “I Serve” is the unit motto.
The 51st Infantry Regiment was constituted in the Regular Army as the 51st Infantry and organized 16 June 1917 at Chickamauga Park, Georgia. The same particulars apply to its 1st, 2nd, and 3rd Battalions, which were originally designated as Companies A, B, and C, as well Companies D, E, and F. Assigned to the 6th Division, the Regiment took part in two World War I campaigns and inactivated in September 1921.
It was relieved from assignment to the 6th Division in 1940 and reactivated on 15 April 1941 as the 51st Infantry (Armored), an element of the 4th Armored Division, then redesignated as the 51st Armored Infantry on 1 January 1942. But the Regiment was broken up and its elements reorganized as elements of the 4th Armored Division; they would be consolidated, some holding new designations, in 1959 to form the 51st Infantry, a parent regiment in the Combat Arms Regimental System. During World War II, the units in the 51st Infantry’s lineage fought in five campaigns, earning a Presidential Unit Citation, two French Croix de Guerre with Palm, and French Fourragere with Palm.
During the Vietnam War, the Regiment took part in five campaigns and was honored with a Valorous Unit Award and two Meritorious Unit Citations. Subsequent battle honors include three campaign streamers and a Meritorious Unit Commendation from the First Gulf War and two Meritorious Unit Commendations in the War on Terrorism, one for service in Iraq in 2007-2008 and another for Afghanistan 2013.
With the inactivation of Company E in 2007, Company F is the only remaining active unit belong to the 51st Infantry Regiment. It was reactivated in 2014 at Fort Bragg, North Carolina, but as of Summer 2023 the unit is not listed as active at Fort Bragg or any other installation.