Is it possible that there were other axes of the Confederate offensive into Union territory during Operation Blackbeard? Such as an invasion of Sequoia or a New Mexico Offensive to eventually reach Mormon rebels? I haven't read many of the books so I may have missed a lot of information from the series.
For my head canon, Operation Blackbeard was more than just Ohio being invaded.
I see Sequoyah being completely liberated early on in the war.
The Union Southwest (OTL Arizona, New Mexico, parts of California) is mostly a battlefield where a lot of hit and run tactics occur. Los Angeles could be bombed from a distance.
Parts of OTL Midwest are not really invaded, but their major cities [Indianapolis, Chicago, Detroit, St. Louis, etc.) are bombed. There are strips of Indiana, Illinois, and Missouri that are under some Confederate control, but are easily taken back after the Battle of Pittsburgh. Per this
image, I also see the cities such as New York City, Philadelphia, and Baltimore being bombed but in never under Confederate control.
Major rebellions in Utah and the former Canadian territories, while not officially part of the operation, are more or less endorsed by Featherston since they give the Union a more difficult time to deal with it.