Head-Quarters, Army of the Potomac,

Dear General; Camp Winfield Scott April 11 1862

I find myself with a siege before me, and as I entertain strong hopes that the result of the operations now impending will be decisive of the present contest, I have taken the liberty to give to this Camp the name of the General under whom I first learned the art of war and whom I have ever regarded as my sincere friend. I hope, General, that the operations emanating from this Camp will not be unworthy of the approbation of the great General whose name it now bears.

When I moved from Fort Monroe, I was deceived by the maps laid before me and supposed that Yorktown could be turned and its garrison cut off by two rapid marches. I therefore moved the Divisions F. J. Porter and Hamilton by the road from Hampton and Big Bethel to Howard 's Bridge, throwing a strong advance guard far enough to the front to force the evacuation of Ship Point; at the same time, I moved the Divisions Smith (W. F.) and Couch from Newport News on Young's Mill; with Scdgwick 's Division, the regular Infantry and Cavalry and the Artillery Reserve, I moved to Big Bethel. The orders for the next day's march were for the left column to move rapidly to Halfway House" 6 miles from Yorktown on the Williamsburg road, in order to cut the communications of the garrison of York; the right column to move upon York and invest it. I moved the reserves to a point 5 miles from Yorktown, whence I could direct it to the support of either column supposing that the left would most require its aid.

It proved, however, to be the ease that the topography of the country was very different from what had been supposed and that the enemy had occupied and strongly entrenched the right bank of the Warwick River, which heads about one-half a mile from Yorktown. The works are formidable, the Artillery pretty heavy. The bed of the Warwick is next to impassable owing to its marshy nature and numerous inundation's. The defences of Yorktown itself and of Gloucester are truly formidable. The water batteries are so heavy as to deter the gun-boats from attacking then,. The roads have been infamous we are working energetically upon them are landing our siege guns, and leaving nothing undone.

We are forced to the use of mortars and heavy guns, although I do not expect, at present, to be obliged to resort to the tedious operations of a formal siege. Franklin 's Division has just been restored to me. With it, I shall attack Gloucester Point.

The Mystic," iron-clad, has been promised me. I shall try to have her run through the passage between York and Gloucester, in order to cut off the supplies and reinforcements constantly received by the rebels by way of York River, and at the same time take their water batteries in reverse.

You are probably aware, General, that, since I commenced this movement, my Army has been weakened by detachments to the extent of nearly 50,000 men. Of these, Franklin's Division (say 11,000) has today been restored to me.

Excuse me, General, for troubling you with this long and hasty letter; but I feel assured that you entertain a strong interest in the movements of this Army; so much so, that I will take the liberty of occasionally writing to you, if it is not disagreeable to you.

I send, with this, a map which will give you a general idea of the position. Tomorrow, I can send you a clear and good one. Only two or three of the enemy's numerous batteries are marked on this.

I am General your sincere & attached friend,

Geo. B. McClellan

Major General