No YOU are misinformed!
The Geneva Agreement of 1954 divided the two countries who had been divided for many many years already, typically from the northern highlands to the southern lowlands. Elections were to be held in 1956. But in the mean time Diem came along in the south. He was just as violently anti-communist as Ho was pro-communist. At that time these were two SEPERATE countries. Diem lead a rebuilding effort of the south from the damage done by the Indo-Chinese War. He then refused to hold reunification elections, again just as vehement as someone like Ho. The U.S. recognized Diem and we had a mutual defense treaty with the south. Diem called on JFK when attacked by the North and JFK/LBJ responded. I suppose we were supposed to support the communist North instead? Or perhaps renig on our agreement with the South? I don't know which would have made the anti-war crowd happier, the outright support of communism or the death of our committment to contain it.
To state that Vietnam was "one" country in the midst of a civil war is simply a falsehood and an oversimplification. These were two different countries forming and the North was the aggressor, NOT the South.
Either way, communism is near dead and capitalism is taking over in Vietnam and China and we can only hope that personal freedoms will follow for the people of those countries.