From Judge Jacob W. Wilkin’s “Personal Reminiscences of General U.S. Grant,” 1907:

One day while riding on the lines, he saw a teamster beating a mule, and riding up to him, ordered him to stop. Wearing an army blouse without shoulder straps, the man did not recognize him and not very politely told him to mind his own business, using profane language, whereupon Grant told his orderly to arrest him and bring him to headquarters. He was turned over to me with orders to tie him up by the thumbs. When the fellow realized that he had used insulting language to General Grant he was the most humiliated man imaginable and protested he did not know it was General Grant. His punishment lasted but a little while and because of my sympathy, was not the most severe of the kind, when I was directed to bring him up to the headquarters tent and there he renewed his protestation that he did not know it was the general he was talking to and that he would not under any circumstances have insulted him. But the general said, ‘You don’t understand, it was not I that was hurt, it was the mule. I could defend myself but the poor dumb animal could say or do nothing for its own protection.’

“He dismissed the culprit with the admonition that he would be closely watched and if again found abusing his team, he would be summarily dealt with.”