That's not an entirely fair characterization. The United States in those days was nothing like it is today. It really was a union of 33 largely independent states by today's standard. The power of the Federal Government was weak compared to today. If you were a citizen of Virginia you were more likely to consider yourself a Virginian than an American. Gen George Thomas was an excellent commander. He served under Grant in the west and won a number of major victories. He was outnumbered at Chickamunga and held against Johnson. He defeated Gen John Bell Hood at Franklin & Nashville, which essentially knocked Tennessee out of the war. He was born in Virginia and chose to remain with the Federal army. You could actually make a case he was more of a traitor to his home and family than Lee was. He lost everything for his choice and even was refused command of the western theater by Lincoln despite Grants suggestion because he was a southerner.
If the war did nothing else if forged a national identity where there was not one before. Had slavery been killed in the crib during the ratification of the Constitution, as it should have been, the US would be a very different country today. So different it's difficult to even guess what it would look like.
Was sort of aware of that, at least from the tales of Lee just following his state. But, lose a civil war, this kind of thing is what happens. Well the best of what happens, I guess. You could end up being hanged