SIR,--You will have received from the Secretary at War a letter, requesting that the quota of the State of Virginia of 100,000 militia be immediately organized and put in readiness for service at the shortest warning, but that they be not actually called out until further requisition. The menacing attitudes which the British ships of war have taken in Hampton Road, the actual blockade of Norfolk, and their having sounded the entrance, as if with a view to pass up to the city, render it necessary that we should be as well prepared there as circumstances will permit. The Secretary at War being gone to New York to arrange a plan of defence for that city, it devolves on me to request that, according to the applications you may receive from the officers charged with the protection of the place, and the information which you are more at hand to obtain than we are here, you will order such portions of the militia as you shall think necessary and most convenient to enter immediately on duty, for the defence of the place and protection of the country, at the expense of the United States. We have, moreover, four gun-boats hauled up at Hampton, and four others on the stocks in Matthews county, under the care of Commodore Samuel Barron, which we consider as in danger. I must request you also to order such aids of militia, on the application of that officer, as you shall think adequate to their safety. Any arms which it may be necessary to furnish to the militia for the present objects, if not identically restored to the State, shall be returned in kind or in value by the United States. I have thought I could not more effectually provide for the safety of the places menaced, than by committing it to your hands, as you are nearer the scene of action, have the necessary powers over the militia, can receive information, and give aid so much more promptly than can be done from this place. I will ask communications from time to time of your proceedings under this charge. I salute you with great esteem and respect. TO CAPTAIN J. SAUNDERS, FORT NELSON. WASHINGTON, July 8, 1807. SIR,--The Secretary at War having proceeded to New York to make arrangements for the defence of that place, your letter to him of July 4th has been put into my hands. I see with satisfaction the promptitude with which you have proceeded in mounting the guns of your fort, and I will count on your continuing your utmost exertions for putting yourself in the best condition of defence possible. With respect to the instructions you ask for, you will consider the proclamation of July 2d as your general instructions, but especially you are to contribute all the means in your power towards the defence of the country, its citizens, and property, against any aggressions which may be attempted by the British armed vessels or any other armed force. I salute you with respect. TO GENERAL MATTHEWS.