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 12 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 may 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 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 of 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 24 pieces of artillery; Banks' Fifth Corps, which embraces the command of General Shields, 19,687 strong, with 41 guns; some 3,652 disposable cavalry and the railroad guards, 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 -

Men.

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

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

There would thus be left for the garrisons and the front of Washington, under General Wadsworth, some 18,000, inclusive of the batteries under instruction. The troops organizing or ready for service in New York, I learn, will probably number more than 4,000. These should be assembled at Washington, subject to disposition where their services may be most required.

I am, very respectfully, your obedient servant,

GEO. B. MCCLELLAN,

Major-General, Commanding.

Brigadier General L. THOMAS, Adjutant-General, U. S. Army.

The following letter from General Barry shows that thirty-two field guns, with men, horses, and equipments, were also left in Washington City when the army sailed. These were the batteries under instruction referred to above:

HEADQUARTERS INSPECTOR OF ARTILLERY,
Washington, December 16, 1862.

GENERAL: It having been stated in various public prints, and in a speech of Senator Chandler, of Michigan, in his place in the United States Senate, quoting what he stated to be a portion of the testimony of Brigadier-General Wadsworth, military governor of Washington, before the joint Senate and House Committee on the Conduct of the War, that Major-General McClellan had left an insufficient force for the defense of Washington, and not a gun on wheels -

I have to contradict this charge as follows:

From official reports made at the time to me (the chief of artillery of the Army of the Potomac), and now in my possession, by the commanding officer of the light artillery troops left in camp in the city of Washington by your order, it appears that the following-named field batteries were left:

Battery C, First New York Artillery, Captain Barnes, two guns; Battery K, First New York Artillery, Captain Crounse, six guns; Battery L, Second New York Artillery, Captain Robinson, six guns; Ninth New York Independent Battery, Captain Morozowicz, six guns; Sixteenth New York Independent Battery, Captain Locke; Battery A, Second Battalion New York Artillery, Captain Hogan, six guns; Battery B, Second Battalion New York Artillery, Captain McMahon, six guns; total, seven batteries, thirty-two guns.

With the exception of a few horses, which could have been procured from the Quartermaster's Department in a few hours, the batteries were all fit for immediate service, excepting the Sixteenth New York Battery, which having been previously ordered,