A question for Vietnam veterans?

I'm looking for an insider's historical perspective. I was born in 1971, by the time of my first memories, this was no longer going on. In history cl, we spent maybe one cl period talking about it, and all the enlightenment I got was that it seemed unpopular and perhaps it was suggested that this was vindicated by the fact that we essentially lost. My father volunteered to go to Vietnam even though he was too old to be drafted by the time they instituted it, but all he really says about it is he believes that if the President says we need to go to war, it's your duty to sign up and go. So I admit, I really understand very little about why we went there and what really happened...all you hear on TV is the protestors' sides, you never really hear anyone defend it. What I'm wondering is, if you were actually there in combat, do you think we were justified in being there, and what is your take on the whole thing? Enlighten me with anything you think I should know.