Precisely at the same time that this evacuation of Manassas gave to McClellan’s enemies an argument against him which they deemed fair and forcible and he deemed unfair and ignorant, two other occurrences added to the strain of the situation.  McClellan immediately put his entire force in motion towards the lines abandoned by the Confederates, not with the design of pressing the retreating foe, which the “almost impassable roads” prevented, but to strip off redundancies and to train the troops in marching.  On March 11, immediately after he had started, the President issued his Special War Order No. 3:  “Major-General McClellan having personally taken the field at the head of the army of the Potomac,... he is relieved from the command of the other military departments, he retaining command of the Department of the Potomac.”  McClellan at once wrote that he should continue to “work just as cheerfully as before;” but he felt that the removal was very unhandsomely made just as he was entering upon active operations.  Lincoln, on the other hand, undoubtedly looked upon it in precisely the opposite light, and conceived that the opportunity of the moment deprived of any apparent sting a change which he had determined to make.  The duties which were thus taken from McClellan were assumed during several months by Mr. Stanton.  He was utterly incompetent for them, and, whether or not it was wise to displace the general, it was certainly very unwise to let the secretary practically succeed him.[165] The way in which, both at the East and West, our forces were distributed into many independent commands, with no competent chief who could compel all to cooeperate and to become subsidiary to one comprehensive scheme, was a serious mistake in general policy, which cost very dear before it was recognized.[166] McClellan had made some efforts to effect this combination or unity in purpose, but Stanton gave no indication even of understanding that it was desirable.

The other matter was the division of the army of the Potomac into four army corps, to be commanded respectively by the four senior generals of division, viz., McDowell, Sumner, Heintzelman, and Keyes.  The propriety of this action had been for some time under consideration, and the step was now forced upon Mr. Lincoln by the strenuous insistence of the Committee on the Conduct of the War.  That so large an army required organization by corps was admitted; but McClellan had desired to defer the arrangement until his generals of division should have had some actual experience in the field, whereby their comparative fitness for higher responsibilities could be measured.  An incapable corps commander was a much more dangerous man than an incapable commander of a division or brigade.  The commander naturally felt the action now taken by the President to be a slight, and he attributed it to pressure by the band of civilian advisers whose untiring hostility he returned with unutterable contempt.  Not only was the taking of the step at this time contrary to his advice, but he was not even consulted in the selection of his own subordinates, who were set in these important positions by the blind rule of seniority, and not in accordance with his opinion of comparative merit.  His irritation was perhaps not entirely unjustifiable.