Allan Pinkerton, The spy in the rebellion; being a true history of the spy system of the United States Army during the late rebellion, revealing many secrets of the war hitherto not made public, compiled from official reports prepared for President Lincoln , General McClellan and the Provost-Marshal-General .

Mrs. Warne was eminently fitted for this task. Of rather a commanding person, with clear-cut, expressive features, and with an ease of manner that was quite captivating at times, she was calculated to make a favorable impression at once. She was of Northern birth, but in order to vouch for her Southern opinions, she represented herself as from Montgomery, Alabama, a locality with which she was perfectly familiar, from her connection with the detection of the robbery of the Adams Express Company, at that place. Her experience in that case, which is fully detailed in “The Expressman and the detective,” fully qualified her for the task of representing herself as a resident of the South.

She was a brilliant conversationalist when so disposed, and could be quite vivacious, but she also understood that rarer quality in womankind, the art of being silent.

The information she received was invaluable, but as yet the meetings of the chief conspirators had not been entered. Mrs. Warne displayed upon her breast, as did many of the ladies of Baltimore, the black and white cockade, which had been temporarily adopted as the emblem of secession, and many hints were dropped in her presence which found their way to my ears, and were of great benefit to me.