George Washington Parke Custis

George Washington Parke Custis (April 30, 1781 – October 10, 1857), was the step-grandson and adopted son of United States President George Washington, the grandson of Martha Washington and the father-in-law of Robert E. Lee. He spent part of his large inherited fortune constructing Arlington House on a plantation that was directly across the Potomac River from Washington, D.C. Custis purchased, preserved and displayed many of George Washington's belongings, wrote historical plays about Virginia, delivered a number of patriotic addresses, and wrote a memoir of his life in the Washington household. After Custis died, his daughter, Mary Anna Randolph Custis, who had married Robert E. Lee, inherited his estate.

George Washington Parke Custis in The Guns of the South
When Robert E. Lee told his wife Mary of his newfound opposition to slavery, she told him that her father, George Washington Parke Custis, would have approved. Although Lee verbally agreed, he silently doubted this hypothesis. The elder Custis had owned hundreds of slaves and emancipated them only in his will, as they would be of no use to him after he was dead. Lee thought that this was magnanimity of a sort, but to his mind it was not enough.