A freed woman became a spy. Then she took down the Confederate White House.

In early 1862, at the height of the Civil War, Confederate President Jefferson Davis became a very paranoid man.

His army was struggling against the Union, which was getting mysteriously better and better at predicting his moves. Davis suspected a mole somewhere in his government, leaking information.

He was right — and wrong.

There was, indeed, a mole. But it was a servant at the Confederate White House in Richmond — a freed slave with a photographic memory who, in addition to caring for his wife’s dresses, slipped the North valuable secrets from Davis’s own desk.

Her name was Mary Bowser. Hers is one of the great but infrequently told spy stories in American history — a shame, say historians and others who write about the Civil War, because it is a tale with an enduring, important lesson.

Bowser used the assumption that she was far less intelligent than her white employers against them.