You can't really talk about Harley history without saying something about Indian motorcycle history so here is a link to it.
http://en.wikipedia.org/wiki/Indian_(motorcycle)
I had a chance to get a 1945 Indian Chief in mint condition several years back but didn't jump on it. Still kicking myself. Probably better that I didn't get it because I would have had it for show only, riding it only a few times a year.

I saw a beautiful Indian one time back in New Hampshire, blue with the inline 4 engine... pristine. Makes one think what would have happened if Indian had gotten all those gov. contracts instead of HD...