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 although he had accurate intelligence concerning the size, composition, and location of his enemy. His initial plans, which proved unrealistic, called for virtually simultaneous recapture of the three lost bases by about 22 May. Except for the few ARVN infantry and engineers that were thrown across the Thi Thinh River to reinforce the An Dien bridgehead, the first major ARVN unit to move into the Triangle was a battalion of the 43rd Infantry, 18th Division, which crossed on Route 14 north of Phú Cường. Shortly reinforced by the rest of the regiment, this element, followed by the 322nd Armored Task