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 .

He had not been in the city a week before he discovered that through some source, the rebels had almost daily news from the front, concerning the movements and plans of the Union troops. This he now determined to ferret out, and the next day, he in a careless manner, inquired of his friend Leroy, how it was, they obtained news so promptly from the front.

“Why,” replied his friend, laughingly, “haven't you heard of the subterranean headquarters?”

“I confess I have not,” replied the detective.

“Then come along with me,” said Leroy. “I ought to have told you about this before, as it is intimately connected with our business.”

He then led the way to the very hotel at which they were stopping, and conducted Curtis to a large and elegantly furnished room on the third floor, and in which were seated a number of gentlemen-some reading, while others were engaged in writing at little tables that were ranged about the room.

“ Here,” said he, laughing, “are the subterranean headquarters, although they are above the top of the ground instead of beneath it. I need not tell you,” he added, “that the name is given as much to mislead as for any other purpose.”

They then took seats at one end of the room where they were alone, and he proceeded with his explanation:

First,