Civil War Histories Microfiche
On top of the file cabinets in the Archives reading room you will find a set of 8 black vinyl binders, about 7" x 11", titled "Various Published Civil War Histories."
These contain microfiche envelopes of film containing dozens of history books, mostly printed in the late 19th and early 20th centuries. I have not seen print versions of most of these in the State Library, these same Archives, or the Main Library here in Indy. Probably all are out of print and maybe not even available on Google.
If you have Indiana Civil War ancestors, you might check out this resource that does not seem to be listed in any Archives "catalog."