I am a Vietnam ERA veteran, serving at the old UA Embassy then located in Karachi 1963-65 when the Gulf of Tonkin happened. Over night I was given the additional duty to receive, RON (Rest Over Night) US walking wounded being air evacuated to Charleston AFB, South Carolina, in the USA. I was wounded just outside Karachi in the first skirmish between Pakistani and India border forces in January, 1965, and missed a month of helping and work with Vietnam War walking wounded as I had to be a "walking wounded" myelf to recover enough to do my job in Karachi.
This said, the Vietnam War was useful, many died brave and historic deaths, others suffered wounds for life, just as I did inside Pakistan.
The major benefit to all civilization was that the Vietnam War led to the eventual failure of Communism as a way of life and governance for Russia when the old USSR invaded Afghanistan, doing the historic search for warm water ports, which of course would have ment then West Pakistan and/or coastal parts of Iran, if not both shorelines and port sites.
Communist China learned that ethnically the Chinese are never going to be welcome in IndoChina, ever, and too, Communist China had to re-think it's "economic model" to recognize that they, China, would do better to develop free enterprise trade zones and join the free world in a limited sense to make a profit and generate capital to have a more modern and progressive Mainland China.
It is only a matter of time before China moves governmentally toward a more democratic governance process, at the least, with elections, free and open, at the major Province levels.
God knows the hearts of all men, and women, and knew the bravery, loyalty, and selfless service and sacrifice many gave to in the line of duty in the Vietnam War againsts the further spread of Communism.