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 .

I then proceeded on to Baltimore, and there I found the greatest amount of excitement that I had yet experienced. I took quarters at the Howard House, and proceeded to inquire closely and carefully into the political situation. I soon found that the fears of the railroad officials were not wholly without foundation. The opposition to Mr. Lincoln's inauguration was most violent and bitter, and a few days' sojourn in this city convinced me that great danger was to be apprehended, and that the sentiment of disunion was far more widespread and deeply rooted than I had before imagined.

The police force of the city was under the control of Marshal George P. Kane, and was almost entirely composed of men with disunion proclivities. Their leader was pronouncedly in favor of secession, and by his orders the broadest license was given to disorderly persons and to the dissemination of insurrectionary information. This individual was subsequently arrested, and, after a brief sojourn in Fort McHenry, fled in 1863 to the more congenial associations of Richmond.

From the knowledge I gained of the situation in Baltimore, I resolved to establish my headquarters in that city. I accordingly engaged a building situated on South street, and in a position where I could receive prompt reports from all quarters of the metropolis.