Dennis, I have always found the "Lost Cause" super interesting. Originally, it was a specific movement in 19th century Southern literary history, fueled by journalism, in which the loss of the WBTS was ascribed to certain causes, specifically Longstreet's delay in bringing up his command in a timely fashion at Gettysburg. There was a real effort by the postwar Lee faction (important: not R.E. Lee himself) to assign blame for the loss of G'burg and the war, by extension, to Longstreet--in large measure in reaction to his post-war political leanings. You will see in the poetry of the day and the newspapers a distinct move to deify Lee with heavy Christ-like symbology. Fallen heroes like Stuart were very much a part of the mythology of the Lost Cause that posited that the South's noble cause could not have been defeated under fair terms, but had to have been the result of dirty dealings. Enter scapegoat Longstreet, the Yankee Quisling.
If you want to read all about it in a super-heavily annotated academic work, read W. G. Piston's "Lee's Tarnished Lieutenant: James Longstreet and His Role in Southern History." WGP is a professor of Civil War history in some college in Missouri.
You may not like his position or his conclusion, but you won't say he didn't do his homework.