http://www.scvcamp469-nbf.com/theblackconfederatesoldier.htm
Nathan Bedford Forrest, upon forming his batallion, offered freedom to 44 slaves he had at the time. All accepted. One later deserted, but the other 43 served honorably. Forrest's personal escort, the best cavalrymen he had, contained eight black soldiers, among the 40 to 90 comprising the escort at various times. When Forrest surrendered, there were over sixty blacks in his troop. He said finer soldiers never served under him. See this site:
http://www.reference.com/browse/Nathan+Bedford+Forrest
As to Lee's loyalty to the Union, it was second only to that he held for his native state and family. Rather than accept command of the United States Army, he resigned because he could not fight against Virginia. He wanted never to fight again, save in defense of his state. Read his letter of resignation, and the one he wrote his sister, at this site:
http://www.sonofthesouth.net/leefoundation/LettersWinfiedScott.htm
Lee stated, in 1868, of the meeting he had with Franklin Blair: “I never intimated to any one, that I desired the command of the United States Army; nor did I ever have a conversation with but one gentleman, Mr. Francis Preston Blair, on the subject, which was at his invitation, and, as I understood, at the instance of President Lincoln. After listening to his remarks, I declined the offer he made me, to take command of the army that was to be brought into the field; stating, as candidly and courteously as I could, that, though opposed to secession, and deprecating war, I could take no part in an invasion of the Southern states.” He is quoted on this site, which has particulars of the meeting and Lee's thoughts:
http://almostchosenpeople.wordpress.com/2010/06/17/lee-offered-command-of-the-union-army/ Stan