On January 27, 1920, the American flag at Mount Vernon flew at half- mast, in memory of a black woman. Visitors that Tuesday would never have guessed whom it honored: a former slave, who had lived long ago in one of the little whitewashed houses to the right of George Washington's mansion. They could easily mistake the lowered Stars and Stripes for a perpetual tribute to the Father of His Country, entombed a few hundred yards away. The superintendent who ordered the gesture that day meant no statement about racial equality. In his words, the flag commemorated a "faithful ex-servant of M.V," a woman who had earned respect by knowing her place. Thirty years earlier nobody knew Mount Vernon better than Sarah Johnson. She had lived there almost half a century by then, longer than even Martha Washington had. Born to a teenage mother in 1844, Sarah grew up surrounded by kin, celebrated the births of new siblings and cousins, grieved for relatives sold away. She trained from child- hood for a lifetime of domestic service, but not the one she got.