I confess that I did not recognize the Morgan I was shown recently. The horses that I knew as a child were the draft/riding Morgans that had been favored working horses in my father's day. Into the 1960's my great uncles plowed their gardens with a horse. I suppose there always was a difference between stock & riding Morgans. In this part of Middle Tennessee black & white walking horses are favored for trail rides. Belgian cross mules predominate. There is a lady who breeds a riding white with black spots. There are quite something to see. During the Civil War, it was the hyper local breeds like the spotted mule that went extinct.
Given your interest in original documents, The Supply for Tomorrow Must Not Fail by Lenette S. Taylor, Kent State University Press is something you want in your library. When Lenette was a grad student, she got a call to examine some boxes discovered in the attic of Quartermaster Captain Simon Perkins Jr.'s family home. He had been an army quartermaster in Nashville & Murfreesboro TN. An army quartermaster was not a career army position. They were civilians who answered not to Rosecrans, e.g., but directly to the Q.M. General in Washington. When he settled his books in 1864, he was supposed to burn the record. Instead, he kept his in the attic. Improbably, no squirrels or rats or leaks or fires destroyed them. When Lenette opened the boxes, she found bundles of documents tied up in faded red tape. She had never seen such a thing before & had to ask her advisor what it meant.
The Perkins archive is, as far as I know, the most complete record of its kind to survive the C.W. My copy of the book looks like a collection of Tibetan prayer flags because of all the postit notes sticking out of it.