"The Choice -- 2004." It will answer all your questions. See this url at:
http://www.pbs.org/wgbh/pages/frontline/shows/choice2004/For time and date of this PBS Frontline program, see this url at:
http://www.pbs.org/tvschedules/In short, upon Kerry's return from his 2 volunteer tours of Navy duty in Vietnam, Kerry protested the Vietnam War. Actively and decisively protested the War. I remember seeing him, personally.
Kerry is a born leader and became active in a vets anti-war organization, and collected stories from other returned Nam vets. He then appeared b4 congress, sworn u/ oath, and re-told those very same stories that were told to him by other returned Nam vets.
He was dislike due to two reasons: (1) he actively protested the war; some Nam vets hated that; and (2) Kerry told congress about his protests with other Nam vets and Kerry recited to congress the vets stories of "war atrocities" according to the Geneva Convention, all of which further incised some Nam vets.
And the hate still brews to this day. Go figure that some Nam vets don't like the idea that they went to war for no damn good reason, would you? They took it negatively against their manhood, their honor, and their character. However, they never reasoned that it wasn't their fault, they internalized it as something against themselves. As does McNeill (is that his name)? who still holds the grudge against Kerry. McNeill (name?), as you will learn in that PBS Frontline program, was set-up by none-other-than Richard Nixon and his cronies.