Bryce:
I don't know how I missed your Jan message, but I did.
Captain John F. Lanneau's "Notebook," (I think that's the title) is a 150 +/- typescript, is at the Greenbville County Library and at Special Collections, Wake Forewst Univ. He was the first captain of the Brooks Troops, B/Hampton Legion Cavalry, which became one of the companies of the 2 S.C. CAV in August 1862. He was defeated for captain by Leonard Williams (his letters are collected as A Boot Full of Memories, cited in the previous message. So Lanneau's diary ends as far as active service is concerned on April 25, 1862.
Lanneau was a professor at Furman College and a large number of the men of the Brooks Troop were students of his. After the war he was a professor at Wake Forest.
Lanneau's diary has loads of detail for that first nine months.
This is of course a secodnary source, but there is a decent biography of M. Calbraith Butler, published 10 years or so ago. It will give you some other citations. There is a small collection of Butler's letters at Duke, but I think only one dates after May 1862.
After fifty years, in the late 1990's/early 2000's, two biographies of Wade Hampton camne out, both pretty decent works, and replacing Giant in Gray, which was totally inadequate, and which had a seeming aversion to primary material. Both of those biographies of Hampton will contain some material on the units of Butler's Brigade, and both are useful.