McClellan was appointed to the command of the Union armies upon the retirement of the veteran General Scott, in November of 1861.  He had been but a captain in the regular army, but his high reputation and brilliant soldierly qualities had led to his being sent abroad to study the organization and movements of European armies; and this brought him into prominence as a military man.  It was soon after McClellan took command that President Lincoln began giving close personal attention to the direction of military affairs.  He formed a plan of operations against the Confederate army defending Richmond, which differed entirely from the plan proposed by McClellan.  The President’s plan was, in effect, to repeat the Bull Run expedition by moving against the enemy in Virginia at or hear Manassas.  McClellan preferred a transference of the army to the region of the lower Chesapeake, thence moving up the Peninsula by the shortest land route to Richmond. (This was a movement, it may be remarked, which was finally carried out before Richmond fell in 1865.) The President discussed the relative merits of the two plans in the following frank and explicit letter to McClellan: 

     EXECUTIVE MANSION, WASHINGTON, D.C.,
     February 3, 1862.

     MAJOR-GENERAL MCCLELLAN.

MY DEAR SIR:  You and I have distinct and different plans for a movement of the Army of the Potomac; yours to be done by the Chesapeake, up the Rappahannock to Urbana, and across to the terminus of the railroad on the York river; mine to move directly to a point on the railroad southwest of Manassas.  If you will give me satisfactory answers to the following questions, I shall gladly yield my plan to yours: 

     1st.  Does your plan involve a greatly larger expenditure of time
     and money than mine?

     2d.  Wherein is a victory more certain by your plan than mine?

     3d.  Wherein is a victory more valuable by your plan than mine?

     4th.  In fact, would it not be less valuable in this, that it
     would break no great line of the enemy’s communication, while mine
     would?

     5th.  In case of a disaster, would not a retreat be more difficult
     by your plan than mine?

     Yours truly, ABRAHAM LINCOLN.

To this communication McClellan made an elaborate reply, discussing the situation very fully, and answering the inquiries apparently to the satisfaction of the President, who consented to the plan submitted by McClellan and concurred in by a council of his division commanders, by which the base of the Army of the Potomac should be transferred from Washington to the lower Chesapeake.  Yet Lincoln must have had misgivings in the matter, for some weeks later he wrote to McClellan:  “You will do me the justice to remember I always insisted that going down the bay in search of a field, instead of fighting at or near Manassas, was only shifting, and not surmounting, a difficulty; that we would find the same enemy, and the same or equal intrenchments, at either place.”