Privately, Lincoln concluded that the Confederacy's slave base had to be eliminated. Copperheads argued that emancipation was a stumbling block to peace and reunification; Republican editor Horace Greeley of the New York Tribune agreed. In a letter of August 22, 1862, Lincoln said that while he personally wished all men could be free, regardless of that, his first obligation as president was to preserve the Union: My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union ... I have here stated my purpose according to my view of official duty; and I intend no modification of my oft-expressed personal wish that all men everywhere could be free.
Pope was then soundly defeated at the Second Battle of Bull Run in the summer of 1862, forcing the Army of the Potomac back to defend Washington. Despite his dissatisfaction with McClellan's failure to reinforce Pope, Lincoln restored him to command of all forces around Washington.
General Robert E. Lee's forces crossed the Potomac River into Maryland, leading to the Battle of Antietam. That battle, a Union victory, was among the bloodiest in American history; it facilitated Lincoln's Emancipation Proclamation in January.
Burnside, against presidential advice, launched an offensive across the Rappahannock River and was defeated by Lee at Fredericksburg in December. Desertions during 1863 came in the thousands and only increased after Fredericksburg, so Lincoln replaced Burnside with Joseph Hooker.