Patrick Cleburne's Chief of Staff.
Resigned. Took off for Mexico just as the defense of Atlanta started.
Second for David S. Terry who killed David Broderick in a duel. Chief Justice vs. Senator.
He returned to California after the cw.
Anybody know any other details about Benham?

He took Cleburne's copy of the British Musketry Manual, repaired to Richmond to write one of the two Confederate marksmanship manual.  In those days there was no "copyright" protection like we do today and so it wasn't uncommon to plagarize when it was in another country.

He was also responsible for training the marksmanship instructor's in Cleburne's division.  The officers easily sidetracked him to regale them with tales from the ante-bellum era.

Got some stuff about him in my first book.

What is the title of your first book and where is it available?
I am curious about where you found out that Cleburne apparently put Belham in charge of the sharpshooters.
I knew at some time Cleburne got a few Whitworths and determined which men were the best marksman.
He realized the need to take out Federal artillery crews at a distance when he did not have his own artillery available or did not wish to draw fire to his own artillery I am guessing.

@atomicbrh  

Look up Sharpshooters by Yee in Ebay.  If you can't find one, PM me.  It's not the little paperback but the hardcover 800 plus page book that you want.