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 .

[152] that the duty of organizing the Ohio volunteers should be assigned to him. To this request no answer was received, and it was afterwards learned that the Governor's letter, owing to the interruption of communications with Washington from all points, had not reached its destination. Failing, therefore, to receive any reply from the general government, and being thus forced to rely upon his own resources, Governor Dennison at once summoned McClellan to Columbus, where the latter applied himself earnestly to the work of organizing the numerous volunteer regiments which offered their services to the country. The State laws were changed in such a manner as to allow the Governor to select commanding officers for these volunteers outside of the members of the State militia, and very soon afterward the Ohio troops were commanded by thoroughly competent men, who had made military movements the subject of scientific study.

On the third day of May a Department of the Ohio was formed, consisting of the combined forces of Ohio, Indiana and Illinois, and this department, by order of General Scott, was placed under the command of General McClellan.

The Ohio troops, as they arrived, were mainly located at Camp Dennison, which was situated in a valley about sixteen miles northwesterly from the city of Cincinnati. This was the largest and the chief camp in the State, and here the volunteers received that