These spies must be arrested at all hazards. They will perhaps escape from Washington but you may be able to take them. You are directed to give the matter your personal attention and spare no effort. Every persons leaving the train at the Relay House, Harper's Ferry or any point between should be arrested, examined and held unless known to be loyal. You should have a force on the lookout at Baltimore and every point to Harper's Ferry and beyond where our lines may be crossed. Colonel Schley and Captains Means and Marsh should be watched and every method taken that your skill and experience can devise. You can render no service equal to the arrest of Alexander and this gang of spies. Acknowledge the receipt of this telegram and keep me advised during the next forty-eight hours where you can be communicated with.

EDWIN M. STANTON.

I have telegraphed General Kelley. You had better communicate with him.

WAR DEPARTMENT, Washington, June 6, 1863.

Colonel FISH, Baltimore:

Alexander is said to be about five feet eight inches high, erect and well made, with keen black eyes and black hair. He wore a heavy black beard a short time ago but may have shaved it off. Captain Summers, who was with Thomas in stealing the steam-boat last year, is one of the party. Another is Leon Ellinger; another is Fritz [Fitspatrick], keeper of the Bull Run Hotel in Richmond. The description of these I have not got. Summers designed to travel in the uniform of an officer of the United States. It is not certain whether they will travel by rail or in a buggy or on horseback, or whether they will go to Baltimore. The fact of their being here yesterday is certain. All strangers on the line should be carefully examined. I will give you any further details as soon as they can be had.

EDWIN M. STANTON.

WAR DEPARTMENT, Washington, June 6, 1863.

Colonel FISH, Baltimore:

Have Poolesville and Edwards Ferry closely watched.

EDWIN M. STANTON,

Secretary of War.

RELAY HOUSE, June 6, 1863.

Hon. E. M. STANTON, Secretary of War:

The operator at this place was able to read by ear and as I had cause to suspect his loyalty I politely requested him to give me possession of the office. He is also the postmaster here and was somewhat indignant; but I told him I would take the responsibility to do as I have and he could report me if he chose. He said he could go into the next room and read everything and I instructed the officer in command here if he did so to arrest him.

W. S. FISH,

Lieutenant-Colonel and Provost-Marshal.