After Operation Lam Son 719, the 1st Brigade conducted Operation Montana Mustang in the eastern half of the Quang Tri Province. The NVA launched indirect fire attacks against FSB's Alpha 4 and Charlie 2 along the DMZ. The 5/4th Arty did a great job in neutralizing the enemy fires, however during an in-coming rocket attack on Charlie 2, where Bravo Battery of the 8Bn 4th Arty was located, the 1st Brigade suffered one its heaviest casualties in a single engagement. On May 21, 1971 a NVA 122mm rocket armed with a delayed fuse struck the top of the Enlisted man's Club bunker exploding inside. The rocket caused the bunker to collapse on top of the many GIs inside. From reports of 8/4 Arty guys who were there, it was a very sad time as GIs from all over the firebase were screaming and yelling, using their hands and anything else that they could use to try to dig out their friends from under tons of dirt and sand bags and large wooden support beams. There were over 60 GIs who had been buried in the bunker. It was reported that most of the GIs killed had been suffocated by the tons of material that had come down on them after the rocket exploded. The rocket attack caused 29 KIAs (all of which are on the WALL in Washington) and 33 WIAs. It was reported that most of the guys who witnessed this catastrophe and had helped to dig out the dead GIs from the downed bunker were so struck with emotion that day that to this day after 30 years it's very hard to "dig up the memories" of long lost friends . . . it was a sad day indeed for our side when that happen.