For two weeks the enemy had been preparing for this retreat; and, beginning their evacuation on the seventh, their whole retrograde movement was completed by March 11, by which date they were secure in their new line of defense, “prepared for such an emergency—­the south bank of the Rappahannock strengthened by field-works, and provided with a depot of food,” writes General Johnston.  No further comment is needed to show McClellan’s utter incapacity or neglect, than that for full two months he had commanded an army of one hundred and ninety thousand, present for duty, within two days’ march of the forty-seven thousand Confederates, present for duty, whom he thus permitted to march away to their new strongholds without a gun fired or even a meditated attack.

General McClellan had not only lost the chance of an easy and brilliant victory near Washington, but also the possibility of his favorite plan to move by water to Urbana on the lower Rappahannock, and from there by a land march via West Point toward Richmond.  On that route the enemy was now in his way.  He therefore, on March 13, hastily called a council of his corps commanders, who decided that under the new conditions it would be best to proceed by water to Fortress Monroe, and from there move up the Peninsula toward Richmond.  To this new plan, adopted in the stress of excitement and haste, the President answered through the Secretary of War on the same day: 

“First.  Leave such force at Manassas Junction as shall make it entirely certain that the enemy shall not repossess himself of that position and line of communication.”

“Second.  Leave Washington entirely secure.”

“Third.  Move the remainder of the force down the Potomac, choosing a new base at Fort Monroe, or anywhere between here and there; or, at all events, move such remainder of the army at once in pursuit of the enemy by some route.”

Two days before, the President had also announced a step which he had doubtless had in contemplation for many days, if not many weeks, namely, that—­

“Major-General McClellan having personally taken the field at the head of the Army of the Potomac, until otherwise ordered, he is relieved from the command of the other military departments, he retaining command of the Department of the Potomac.”

This order of March 11 included also the already mentioned consolidation of the western departments under Halleck; and out of the region lying between Halleck’s command and McClellan’s command it created the Mountain Department, the command of which he gave to General Fremont, whose reinstatement had been loudly clamored for by many prominent and enthusiastic followers.

As the preparations for a movement by water had been in progress since February 27, there was little delay in starting the Army of the Potomac on its new campaign.  The troops began their embarkation on March 17, and by April 5 over one hundred thousand men, with all their material of war, had been transported to Fortress Monroe, where General McClellan himself arrived on the second of the month, and issued orders to begin his march on the fourth.