We were in Vietnam a number of years before the Gulf of Tonkin incident. When I shipped to Germany in 1960 the Army was asking for volunteers to go to Vietnam. My future wife knew a fellow who was already there. in 1959. I am not sure exactly when the first volunteers went there, but it was while Eisenhower was president.
This is true.
For nearly a decade, the US helped the French in training and logistic support.
The French pulled out, leaving the US holding the bag.
The "gulf of Tonkin" was merely an excuse (imo) to ramp up the US involvement and allow the beginnings of gathering public support.
Eventually, the lies and deception were exposed, but by then, the nation had already become embroiled in huge domestic issues and distractions.
Vietnam wasn't lost by our good soldiers, it was lost at home through distraction and coverup.
Same thing that is going on in the various conflicts, today.