blockading vessels, and threatens to sweep our whole flotilla from Chesapeake Bay. Under these circumstances it is of the last importance to capture of destroy the Merrimac, and the whole wealth and power of the United States will be at command for that purpose. As this movement was anticipated and the subject of discussion between you and myself last December, your have no doubt thought of various modes by which it could be met and overcome most promptly. The Secretary of War desires you quietly to call a meeting of from three to nine persons, at your discretion, of the best judgment in naval engineering and warfare, to meet immediately at your farther's house or some other convenient and suitable place, and to sit as a committee to devise the best plan of speedy accomplishing the capture or destruction of the Merrimac. I would suggest the name of Abram S Hewitt as a member of the committee. You will bear in mind that every hour's delay to destroy the merrimac may result in incalculable damage to the United States, and that the plan or plans for her destruction should be submitted at the earliest hour practicable for the approval of this Department, to the end that their execution may not be necessarily delayed a moment. To enable you to communicate hourly with this Department, the telegraphic company is directed to transmit all messages from you at the expense of the Government.

Acknowledge this dispatch the moment you receive it. Spare no pains or expense to get the committee together immediately. Act with the utmost energy. You and each member of the committee will consider this whole matter confidential.

P. H. WATSON,

Assistant Secretary of War.

HEADQUARTERS ARMY OF THE POTOMAC,
Washington, March 9, 1862.

COMMANDING OFFICERS Fort Delaware; Fort Mifflin; New York Harbor, N. Y.; Newport, R. I.: Fort Trumbull, New London; Boston Harbor; Portland, Me.:

The rebel iron-clad steamer Merrimac has destroyed two of our frigates near Fort Monroe and finally retired last night to Craney Island. She may succeed in passing the batteries and go to sea. It is necessary that you at once place your post in the best possible condition for defense, and do you best to stop, her should she endeavor to run by. Anything that can be effected in the way of temporary batteries should be done at once.

GEO. B. McCLELLAN,

Major-General, U. S. A.

HEADQUARTERS,
Baltimore, March 9, 1862.

Colonel GOUVERNEUR K. WARREN,

Commanding Fort Federal Hill:

COLONEL: The Merrimac has come down from Norfolk and destroyed the Cumberland and the Congress. She may pass Fort Monroe and come here. You will have Forth Federal Hill and Marshall prepared for action, and take every precaution for their security against attack. This is especially necessary in regard to the latter, which has a very small garrison.