Josh Marshall has a post on Kerry's service records, which are now available online. It seems to be all there from the little I know about such things from my dad's records.
Josh specifically links to a document that begins, "I request duty in Vietnam."
That's pretty easy to distinguish from an air national guard request.
I don't know much about the protocol and practical effect of requests such as Kerry's, but my father has told me a little. He enlisted. It wasn't an uncommon tactic, especially if you knew your draft number meant you didn't have long to wait. By volunteering, apparently, you had a better chance of driving a supply truck well behind the front line, or other, less in-the-line-of-fire assignments.
Not my dad, though.
He signed up and wanted to be right in there. Why? Good question, and one I posed awhile back.
He says he grew up reading about WWII and other wars, battles, heroes, leaders, legends, etc. As a boomer, I suppose that was common since he was born to Greatest Generation parents (my grandfather served in Italy, my other grandfather stormed the beach at Normandy). My dad says he always wanted to know why someone would "take that hill" when ordered. Why do soldiers follow? Go run up that hill in the face of gun and heavy artillery fire, and know that you - and/or many of your friends - are quite likely going to get shot and/or die. Okay, sure - are you nuts?
So he left Gonzaga after his sophomore year and went to Vietnam (9th Infantry).
So what's the answer? Why do they do it?
He doesn't know.
But he was shot several times, earned a purple heart and bronze star himself trying to figure it out.
Why do we fight? I don't mean why in terms of philosophy, paradigms, policies, etc. I mean, why does anyone, singular, and individual, pick up a gun and run in front of other people with guns. When does self-preservation take a holiday? At the start of boot camp? In the adrenaline rush of battle? Is it from playing too many violent video games?
I don't know. And neither does my primary source. I wish I were brave enough to investigate for myself - but right there is part of the answer, I think. "I wish" to go into battle? Curiosity kills a lot. We go up the mountain because it's there - to see if we can - to see what we can see. It applies to everyting in the human experience. War. Love. Actually - if you boil it down, that kind of is the human experience - everything is on the spectrum between the two.