General McClellan (before Yorktown) has Richmond for his object, with Washington under his safe-keeping. The immediate interest of the war is connected with the above indications, and all adjacent operations are incidental.

It is necessary to break the line of communication between Richmond and Corinth. This may be done by Buell, and if he should occupy the Cumberland Gap near the railroad this object will be sufficiently accomplished. If some point east of the Gap be also made an object (as proposed by the President), it will require a large force to reach and maintain it, or that force might be destroyed by the enemy. Instead, therefore, of employing a force necessary for seizing a point east of the Gap, it might be better to employ a less force in the protection of the Baltimore and Ohio Railroad (the duty assigned to General Fremont.) From present indications it might be better, instead of sending to the Mountain Department all of the force desired by its commander, to divide that force-one part to go to him for the protection of the Baltimore and Ohio Railroad and the country immediately south of it, and the other part to strengthen McClellan's right,now occupied by Shields, the route from Richmond in that direction being open to the enemy, who, though not likely to take it, might be invited by its weakness to make some desperate attempt similar to one already made by Jackson upon Shields.

A movement from McClellan's left is know to the enemy; hence nothing is more natural than a blow on McClellan's right. Nothing has intervened since that made a few days since to prevent a repetition of it with a larger force.

If McClellan should fail (at Yorktown)-not likely to happen; but if he should fail-what would be the movement of the enemy? It might be a desperate attempt to turn the right of the Army of the Potomac (the Shenandoah Valley). This should be guarded against by a part of the force called for by Fremont, instead of sending that force to cut the Richmond and Knoxville Railroad the success of which might even aid in forcing the enemy to make some desperate attempt on the right of Washington.

N.

WASHINGTON, April 9, 1862.

Major-General McCLELLAN:

MY DEAR SIR: Your dispatches complaining that you are not properly sustained, while they do not offend me, do pain me very much.

Blenker's division was withdrawn from you before you left here, and you knew the pressure under which I did it, and, as I thought, acquiesced in it-certainly not without reluctance.

After you left I ascertained that less than 20,000 unorganized men, without a single field battery, were all you designed to be left for the defense of Washington and Manassas Junction, and part of this even was to go to General Hooker's old position. General Banks' corps, once designed for Manassas Junction, was divided and tied up on the line of Winchester and Strasburg, and could not leave it without again exposing the Upper Potomac and the Baltimore and Ohio Railroad. This presented (or would present, when McDowell and Sumner should be gone) a great temptation to the enemy to turn back from the Rappahannock and sack Washington. Me explicit order that Washington should, by the judgment of all the commanders of corps, be left entirely secure had been neglected. It was precisely this that drove me to detain McDowell.