The History Channel's Today in History page states that Maj. Dale R. Ruis and Master Sgt. Chester M. Ovnand were the first Americans killed in the American phase of the Vietnam War, 58 years ago today. Neither of these heroes has a WikiTree profile. If you are interested in honoring Vietnam veterans, consider joining the Vietnam War Project. This page also has a tag you can add to your Vietnam veteran profiles.
It is Dale Buis not Dale Ruis.
https://en.wikipedia.org/wiki/Dale_R._Buis