Having been adopted by the US Army in 1863, charges would be brought by someone in the chain of command, and what is now an Article 15 conducted to see if charges would go forward to court martial. Getting Sherman charged would have been a major obstacle to overcome. At the time of his March to the Sea, the only officer who outranked Sherman would be Grant, and he was not likely to try him. Complaints by civilians at the time would have been pushed aside or ignored.

BTW, The Navy and Marine Corps served under Rocks and Shoals until the UCMJ came into being. I'm not sure when flogging went out of favor. Stan