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 50th Infantry, 25th Division, were already in this area. Meanwhile, the 46th Infantry and one battalion of the 50th moved into the plantations north of Phú Hòa District Town to prevent PAVN infiltration across the Saigon River. Along Route 7, the 9th Infantry advanced without incident until 19 November when sharp fighting west of Base 82 resulted in over 40 ARVN soldiers wounded. The PAVN withdrew leaving 14 dead and many weapons and radios behind. The next morning, Reconnaissance Company, 9th Infantry, entered Rach Bap unopposed. The Iron Triangle campaign was virtually over, although mopping-up operations continued in the south