Could use some help on US political history

[mrgorth]

I was listening to this story on post civil war reconstruction on NPR's Fresh Air yesterday:

http://www.npr.org/templates/story/story.php?storyId=5133942

The author was recounting how freed slaves were offered land. The old "40 acres and a mule" thing. Then Andrew Johnson, a democrat, got into office. According to the author he was a racist and he flat out gave whatever land these slaves got back to the previous landowners. This engendered a sense of betrayal among the blacks and rightly so. He futhermore went on to recount how the republican congress went around Johnson by passing one of the first civil rights acts. So, what I'm trying to figure out is how we get from THOSE republicans to the use of the "southern strategy". I mean, I know parties are dynamic and go through natural changes. We've also previously discussed how Teddy Roosevelt and Ike wouldn't be welcome in today's republican party. There just seems to be one key piece missing. The most obvious element sticking out to me is the "southern democrats" (note: not the type that post here), that if this element would morph into todays republicans and if there are any Teddy Roosevelt type republicans left they would morph into a contemporary democrat, the parties would at least seem more homogenous. Unfortunately for the dems in this equation republicans seem to care more about party unity than the dems do so they would wind up on the short end of the stick. What am I missing? Thanks.