General Dix has, after guarding the railroads under his charge, sufficient troops to give him 5,000 for the defense of Baltimore, and 1,988 available for the Eastern Shore, Annapolis, &c. Fort Delaware is very well garrisoned by about 400 men.

The garrisons of the forts around Washington amount to 10,600 men; other disposable troops now with General Wadsworth being about 11,400 men. The troops employed in guarding the various railways in Maryland amount to some 3,359 men. These it is designed to relieve, being old regiments, by dismounted cavalry, and to send forward to Manassas.

General Abercrombie occupies Warrenton with a force which, including Colonel Geary, at White Plains, and the cavalry to be at his disposal, will amount to some 7,780 men, with twelve pieces of artillery.

I have the honor to request that all the troops organized for service in Pennsylvania and New York and in any of the Eastern States my be ordered to Washington. I learn from Governor Curtin that there are some 3,500 men now ready in Pennsylvania. This force I should be glad to have sent at once to Manassas. Four thousand men from General Wadsworth I desire to be ordered to Manassas These troops, with the railroad guards above alluded to, will make up a force under the command of General Abercrombie to something like 18,639 men. It is my design to push General Blenker's division from Warrenton upon Strasburg. He should remain at Strasburg long enough to allow matters to assume a definite form in that region before proceeding to his ultimate destination.

The troops in the valley of the Shenandoah will thus-including Blenker's division, 10,028 strong, with twenty-four pieces of artillery; Banks' Fifth Corps, which embraces the command of General Shields, 19,687 strong, with forty-one guns; some 3,652 disposable cavalry and the railroad guard, about 2,100 men-amount to about 35,467 men.

It is designed to relieve General Hooker by one regiment, say 850 men, being, with some 500 cavalry, 1,350 men on the Lower Potomac.

To recapitulate:

At Warrenton there is to be................. 7,780

At Manassas, say............................ 10,859

In the valley of the Shenandoah............. 35,467

On the Lower Potomac........................ 1,350

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In all...................................... 55,456

There would thus be left for the garrisons and the front of Washington, under General Wadsworth, some 18,000 men, exclusive of the batteries under instructions.

The troops organizing or ready for service in New York I learn will probably number more that 4,000. these should be assembled at Washington, subject to disposition where their services may be most needed.

I am, very respectfully, your obedient servant,

GEO. B. MCCLELLAN,

Major-General, Commanding.

THIRTY-FIFTH DAY.

COURT-ROOM, COR. FOURTEENTH AND PA. AVENUE,

Washington, D. C., January 5, 1863.

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The recorder read from the record books pertaining to the Headquarters