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 sent the 141st Regiment, 7th Division south from its position along Highway 13, north of Lai Khê, to reinforce the 9th Division north of Base 82. The 9th Division meanwhile began shifting the 272nd Regiment north from the southern part of the Iron Triangle to assist in the defense of Base 82 and Rach Bap. The summer monsoon had arrived in Bình Dương Province and rains and low cloud cover further reduced the effectiveness of RVNAF support for the attack. A dense rubber plantation northwest of Base 82 provided excellent concealment for supporting defensive positions and observation of local Route