Iron Brigade and was previously called the "Black Hat" Brigade. The 3rd Brigade Combat Team, 1st Infantry Division was known as the Iron Brigade from its formation in 1917 through World War I, World War II and Vietnam, until some time in the early 2000s when, for reasons that are still unclear, the name was changed to Duke Brigade. The unit crest was an Iron Cross in a triangle, it appears that that was also changed. The 3rd Brigade of the 4th Infantry Division is also known as the Iron Brigade. Its unit crest is similar to the medals issued to veterans
Battle of the Iron Triangle Lt. Gen. Dư Quốc Đống. General Đống immediately surveyed the situation in the Iron Triangle and reviewed the plan of his predecessor, which as modified became operation Quyet Thang 18/24 (Operation Will to Victory). Battalions from all three divisions of the corps were committed; D-Day was 14 November. The 9th Infantry, 5th Division started from An Dien and marched west, along Route 7, past Base 82 toward Rach Bap. The 48th and 52nd Regiments, 18th Division crossed the Thi Thinh River south of Ben Cat and entered the Iron Triangle and attacked west toward the Saigon River. Elements of the