Cpl. Zager received the Silver Star posthumously for calling in air and ground support though mortally wounded during an NVA ambush in which he was in the point vehicle during a mine sweeping mission.  The post below is from the Vietnam Memorial Virtual Wall webpage.
"I was a road grader operator for the 630th combat engineers , we supported John's company with heavy equipment when needed. It was raining off and on that morning the dirt roads to the fire support base were real muddy, my road grader kept getting stuck in the mud so I was told to stay behind. It was John's first day to drive the jeep in front of the convoy the jeep was the first thing the NVA hit. John was mortally wounded but still managed to call on the phone for help. If it wasn't for him calling for help the NVA would have had the convoy pinned down longer then it did. Your a hero John and I know your family is proud of you. Three Americans were killed that day and three others where badly wounded, the Sargeant that was in the back of the jeep took about three rounds in the chest but lived. NVA killed was approx 15. We had a memorial service the next day in the rain for John and the other solders. John was loved by all. My sincerest sorrow for the John's family.  Gary Demers.