commanding Fourth Army Corps, after the examination of the enemy's defenses on the left, before alluded to, addressed the following letter to the Honorable Ira Harris, United States Senate, and gave me a copy. Although not strictly official, it describes the situation at the time in some respects so well that I have taken the liberty of introducing it here:

HEADQUARTERS FOURTH CORPS, Warwick Court-House, Va., April 7, 1862.

MY DEAR SENATOR: The plan of campaign on this line was made with the distinct understanding that four army corps should be employed, and that the Navy should co-operation in the taking of Yorktown, and also (as I understood it) support us on our left by moving gunboats up James River.

To-day I have learned that the First Corps, which by the President's order was to embrace four divisions and one division (Blenker's) of the Second Corps, have been withdrawn altogether from this line of operations and from the Army of the Potomac. At the same time, as I am informed, the Navy has not the means to attack Yorktown, and is afraid to send gunboats up James River for fear of the Merrimac.

The above plan of campaign was adopted unanimously by Major-General McDowell and Brigadier-General Sumner, Heitzelman, and Keyes, and was concurred in by Major-General McClellan, who first proposed Urbana as our base.

This army being reduced by 45,000 troops, some of them among the best in the service, and without the support, of the Navy, the plan to which we are reduced bears scarcely any resemblance to the one I voted for.

I command the James River column, and I left my camp near Newport News the morning of the 4th instant. I only succeeded in getting my artillery ashore the afternoon of the day before, and one of my divisions had not all arrived in camp the day I left, and for the want of transportation has not yet joined me. So you will observe that not a day was lost in the advance, and in fact we marched so quickly and so rapidly, that many of our animals were twenty-four and forty-eight hours without a ration of forage. But, notwithstanding the rapidity of our advance, we were stopped by a line of defense 9 or 10 miles long, strongly fortified by breastworks erected nearly the whole distance behind a stream or succession of ponds, nowhere fordable, one terminus being Yorktown and the other ending in the James River, which is commanded by the enemy's gunboats. Yorktown is fortified all around with bastioned works, and on the water side it and Glouncester are so strong that the Navy are afraid to attack either.

The approaches on one side are generally through low, swampy, or thickly-wooded ground, over roads which we are obliged to repair or to make before we can get forward our carriages. The enemy is in great force, and is constantly receiving re-enforcements from the two rivers. The line in front of us is therefore one of the strongest ever opposed to an invading force in any country.

You will then ask why I advocated such a line for our operations. My reasons are few, but I think good.

With proper assistance from the Navy we could take Yorktown, and then, with gunboats on both rivers, we could beat any force opposed to us on Warwick River, because the shot and shell from the gunboats would nearly overlap the Peninsula; so that if the enemy should retreat - and retreat he must - he would have a long way to go without rail or steam transportation, and every soul of his army must fall into our hands or be destroyed.

Another reason for my supporting the new base and plan was that this line, it was expected, would furnish water transportation nearly to Richmond.

Now, supposing we succeed in breaking through the line in front of, us what can we do next? The roads are very band, and if the enemy retains command of James River and we do not first reduce Yorktown it would be impossible for us to subsist this army three marched beyond where it is now. As the roads are at present it is with the utmost difficulty that we can subsist it in the position it now occupies.

You will see, therefore, by what I have said that the force originally intended for the capture of Richmond should be all sent forward. If I thought the four army corps necessary when I supposed the Navy would co-operate, and when I judged of the obstacles to be encountered by what I learned from maps and the opinions of officers long stationed at Fort Monroe and from all other sources, how much more should I think the full complement of troops requisite now that the Navy cannot co-operate, and now that the strength of the enemy's lines and the number of his guns and men prove to be almost immeasurably greater than I had been led to expect. The line in front of us, in the opinion of all the military men here who are at all competent to judge, is one of the strongest in the world, and the force of the enemy capable of being increased beyond the numbers we now have to oppose to him. Independently of the strength of the lines in front of us and of the force of the enemy behind them, we