Lincoln was a lawyer and the tools of his trade were words, (edited by administration) words. The Unionists called the WBTS the War of the Rebellion because it was politically correct, not for being legally or morally correct. Everyone knew it was a war between nations with the Dixie Cartel, bi-lateral conscription, surrenders and numerous other proofs.
Like most modern politicians, Lincoln's words were often in conflict with his actions, which calls his Carl Sandberg image and his beliefs into question.