“General Burnside wishes to cross the Rappahannock with his army, but his grand division commanders all oppose the movement.  If in such a difficulty as this you do not help, you fail me precisely in the point for which I sought your assistance.  You know what General Burnside’s plan is, and it is my wish that you go with him to the ground, examine it as far as practicable, confer with the officers, getting their judgment and ascertaining their temper; in a word, gather all the elements for forming a judgment of your own, and then tell General Burnside that you do approve, or that you do not approve, his plan.  Your military skill is useless to me if you will not do this.”

Halleck’s moral and official courage, however, failed the President in this emergency.  He declined to give his military opinion, and asked to be relieved from further duties as general-in-chief.  This left Mr. Lincoln no option, and still having need of the advice of his general-in-chief on other questions, he indorsed on his own letter, “withdrawn because considered harsh by General Halleck.”  The complication, however, continued to grow worse, and the correspondence more strained.  Burnside declared that the country had lost confidence in both the Secretary of War and the general-in-chief; also, that his own generals were unanimously opposed to again crossing the Rappahannock.  Halleck, on the contrary, urged another crossing, but that it must be made on Burnside’s own decision, plan, and responsibility.  Upon this the President, on January 8, 1863, again wrote Burnside: 

“I understand General Halleck has sent you a letter of which this is a copy.  I approve this letter.  I deplore the want of concurrence with you in opinion by your general officers, but I do not see the remedy.  Be cautious, and do not understand that the government or country is driving you.  I do not yet see how I could profit by changing the command of the Army of the Potomac; and if I did, I should not wish to do it by accepting the resignation of your commission.”

Once more Burnside issued orders against which his generals protested, and which a storm turned into the fruitless and impossible “mud march” before he reached the intended crossings of the Rappahannock.  Finally, on January 23, Burnside presented to the President the alternative of either approving an order dismissing about a dozen generals, or accepting his own resignation, and Mr. Lincoln once more had before him the difficult task of finding a new commander for the Army of the Potomac.  On January 25, 1863, the President relieved Burnside and assigned Major-General Joseph Hooker to duty as his successor; and in explanation of his action wrote him the following characteristic letter: