of the plan for the Peninsula movement. But the engagement between the Monitor and Merrimac on the 9th of March demonstrated so satisfactorily the power of the former, and the other naval preparations were so extensive and formidable, that the security of Fort Monroe as a base of operations was placed beyond a doubt, and although the James River was closed to us, the York River with its tributaries was still open as a line of water communication with the Fortress. The general plan, therefore, remained undisturbed, although less promising in its details than when the James River was in our control.
On Sunday, the 9th of March, information from various sources made it apparent that the enemy was evacuating his positions at Centreville and Manassas as well as on the Upper and Lower Potomac. The President and Secretary of War were present when the most positive information reached me, and I expressed to them my intention to cross the river immediately, and there gain the most authentic information prior to determining what course to pursue.
The retirement of the enemy towards Richmond had been expected as the natural consequence of the movement to the Peninsula, but their adoption of this course immediately on ascertaining that such a movement was intended, while it relieved me from the results of the undue anxiety of my superiors and attested the character of the design, was unfortunate in that the then almost impassable roads between our positions and theirs deprived us of the opportunity for inflicting damage usually afforded by the withdrawal of a large army in the face of a powerful adversary.
The retirement of the enemy and the occupation of the abandoned positions which necessarily followed presented an opportunity for the troops to gain some experience on the march and bivouac preparatory to the campaign, and to get rid of the superfluous baggage and other "impedimenta" which accumulates so easily around an army encamped for a long time in one locality.
A march to Manassas and back could produce no delay in embarking for the Lower Chesapeake, as the transports could not be ready for some time, and it afforded a good intermediate step between the quiet and comparative comfort of the camps around Washington and the rigors of active operations, besides accomplishing the important object of determining the positions, and perhaps the future designs, of the enemy, with the possibility of being able to harass their rear.
I therefore issued orders during the night of the 9th of March for a general movement of the army the next morning towards Centreville and Manassas, sending in advance two regiments of cavalry under Colonel Averell, with orders to reach Manassas if possible, ascertain the exact condition of affairs, and do whatever he could to retard and annoy the enemy if really in retreat; at the same time I telegraphed to the Secretary of War that it would be necessary to defer the organization of the army corps until the completion of the projected advance upon Manassas, as the divisions could not be brought together in time. The Secretary replied, requiring immediate compliance with the President's order; but on my again representing that this would compel the abandonment or postponement of the movement to Manassas, he finally consented to its postponement.
At noon on the 10th of March the cavalry advance reached the enemy's lines at Centreville, passing through his recently-occupied camps and works, and finding still burning heaps of military stores and much valuable property.
Immediately after being assigned to the command of the troops around.