He was not the owner of the slaves at Arlington or the other Custis properties. They had been the property of George Washington Parke Custis. He was Mary Custis Lee’s father. When he died in Dec 1857, his will named Lt.Col. Lee as the estate executor. In his will, Custis authorized the executor of the estate to free all of the slaves if the estates finances were in good order or keep them as slaves but free them within 5 years of his death. Lee determined that the slaves needed to be retained for the financial well being of the Arlington estate and so he kept the former Custis slaves in bondage. The slaves of the Custis estate were freed by lee as required in the Custis will on Dec 29 1862. Exactly 5 years after GWP Custis’s death.
Thank you for that clarification. I’ll have to re read his biography.
Custis died October 27, 1857 and the last of the slaves were freed on December 29, 1862. Slightly more than five years but given all Lee had on his plate then it's perhaps understandable.