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 Triangle on the night of 2/3 June, The fighting at An Dien wos especially fierce on 3 June as the PAVN used tanks against ARVN infantry. Armed with light antitank weapons, ARVN infantry knocked out at least 4 tanks in the final day of the battle. On 4 June, troops of the 18th ARVN Division finally entered An Dien and on the 5th overran the last position of the 95C Regiment, which had since been reinforced by elements of the 271st Regiment. On the morning of the 5th, two battalions of the 48th and two of the 52nd were holding