How and why did public opinion about the conflict in Vietnam change?

As reports from the field became increasingly accessible to citizens, public opinion began to turn against U.S. involvement, though many Americans continued to support it. Others felt betrayed by their government for not being truthful about the war. This led to an increase in public pressure to end the war.

Those who viewed Vietnam as "not a mistake" would never again be in the majority. The polls continued trending against the war until U.S. troops were withdrawn in 1973. Only two polls showed a significant change.  Vietnam was a battleground in the Cold War, when the United States and Soviet Union grappled for world domination. By war's end, North and South Vietnam would be reunited, but at great cost.

thomas jefferson is the answer