Shelby's Iron Brigade 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 of the both Western and the Eastern
Battle of the Iron Triangle whose troops had been in heavy combat for a month, with the 5th Division. Instead of relieving the 18th, General Thuần decided to try his armor again. Holding the infantry in position, he sent the 318th and 322nd Task Forces back into the Triangle, one north of Route 7, the other generally along the road. The PAVN's antitank defenses, primarily employing the 82-mm. recoilless gun, stopped the attack once again, destroying 13 M113 armored personnel carriers and 11 M48 tanks between 27 June and 1 July, even though ARVN artillery and the RVNAF supported the attack with 43,000 rounds and