Here's some starter material:

Following his stepfather’s lead, George Washington Custis included a provision in his will for the emancipation of his slaves. But before it could be operative, circumstances required it be interpreted in a court of law. One of the female slaves held at Arlington, possibly Custis's mistress, claimed after his death that Custis had promised her his will would provide for emancipation immediately upon his death. The slaves obtained support for this claim from white persons who came from across the Potomac and went among them in the fall of 1857, telling them that Custis's will had made them free immediately.

The issue became a matter of litigation in the probate court of Alexandria County after several of the male members of the Bingham slave family, Reuben, Henry, Edward and Austin, refused to accept assignments to work at jobs off the premises of Arlington.

Reuben, the leader of the rebellion, told General Lee, who was acting then as executor and manager of Arlington Plantation, that he and his brothers were as free as he. A melee ensued between them when General Lee organized a posse to forcibly remove Reuben and his brothers to the Arlington county jail.

After a short struggle, the rebelling slaves were subdued and taken to the jail where they were held until taken south to Richmond under guard. Wesley and Mary Norris, siblings in the Norris slave family, fled across the Potomac into Maryland at this time, but were caught before they reached the Pennsylvania line and returned to Virginia: whereupon they too were sent down to Richmond.

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http://civilwartalk.com/threads/wesley-norris.89653/

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History deliberately being changed

http://civilwartalk.com/threads/history-deliberately-being-changed.73833/

http://americancivilwar.com/authors/Joseph_Ryan/Articles/General-Lee-Slaves/General-Lee-Family-Slaves.html

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Under his legal authority as executor of the Custis Estate, vested in him by the common law of Virginia, General Lee pronounced the Custis slaves "forever set free from slavery." The deed was recorded on January 2, 1863 in the Henrico County courthouse, located in Richmond, one day after the operative date of President Lincoln's extralegal Emancipation Proclamation. Among the names included in General Lee's deed of manumission are Wesley and Mary Norris and Reuben Bingham and his three brothers.