While the lineage of the 108th Cavalry Regiment displayed on the U.S. Army Center of Military History Web site only goes back to 1959, the insignia’s redesignation dates paint a more complete picture of the units from which the unit descended.
The 108th Cavalry Regiment Distinctive Unit Insignia—also referred to as a unit crest or a DUI—was originally approved for the 108th Cavalry Regiment on 1 November 1929. On 4 January 1952 it was redesignated for the 105th Antiaircraft Artillery Automatic Weapons Battalion, and about eight-and-a-half years (29 August 1960) later it was redesignated for the 139th Armor Regiment. It was next authorized for the 139th Cavalry Regiment in January 1966, then for the 205th Engineer Battalion on 26 June 1958. Rescinded on 2 September 1976, it was reinstated and redesignated for the 8th Cavalry Regiment on 28 September 1996.
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.As you can see above, there was an iteration of the 108th Cavalry Regiment that served in World War II and which at some point following the war was redesignated as an Antiaircraft unit. But on 2 September 1995 the unit was resurrected in the Georgia and Louisiana Army National Guard as the 108th Cavalry, a parent regime in the U.S. Army Regimental System, with its Troops A and B organized from existing elements and made elements of the 256th Infantry Brigade and 48th Infantry Brigade, respectively.
A decade later, the regiment was redesignated as the 108th Cavalry Regiment in 2006, and the following year it was reorganized to consist of 2nd Squadron, an element of the 256th Infantry Brigade, and Troop E, an element in the 48th Infantry Brigade. As of Summer 2023, the Regiment consists of the 1st Squadron, assigned to the 48th Infantry Brigade Combat Team, Georgia Army National Guard and the 2nd Squadron, assigned to the 256th Infantry Brigade Combat Team, Louisiana Army National Guard.