In November 1862, U.S. President Abraham Lincoln needed to demonstrate the success of the Union war effort before the Northern public lost confidence in his administration. Confederate armies had been on the move earlier in the fall, invading Kentucky and Maryland. Although each had been turned back, those armies remained intact and capable of further action. Lincoln urged Major General Ulysses S. Grant to advance against the Confederate stronghold of Vicksburg, Mississippi. He replaced Maj. Gen. Don Carlos Buell with Maj. Gen. William S. Rosecrans, hoping for a more aggressive posture against the Confederates in Tennessee, and on November 5, seeing that his replacement of Buell had not stimulated Maj. Gen. George B. McClellan into action, he issued orders to replace McClellan with Maj. Gen. Ambrose Burnside in command of the Army of the Potomac in Virginia. However, Burnside felt himself unqualified for army-level command and objected when offered the position. He accepted only when it was made clear to him that McClellan would be replaced in any event and that an alternative choice for command was Maj. Gen. Joseph Hooker, whom Burnside disliked and distrusted. Burnside assumed command on November 7.

Burnside's plan was to cross the Rappahannock River at Fredericksburg in mid-November and race to the Confederate capital of Richmond before Lee's army could stop him. Bureaucratic delays prevented Burnside from receiving the necessary pontoon bridges in time and Lee moved his army to block the crossings. When the Union army was finally able to build its bridges and cross under fire, direct combat within the city resulted on December 11–12. Union troops prepared to assault Confederate defensive positions south of the city and on a strongly fortified ridge just west of the city known as Marye's Heights.

On December 13, the Left Grand Division of Maj. Gen. William B. Franklin was able to pierce the first defensive line of Confederate Lt. Gen. Stonewall Jackson to the south, but was finally repulsed. Burnside ordered the Right and Center Grand Divisions of major generals Edwin V. Sumner and Joseph Hooker to launch multiple frontal assaults against Lt. Gen. James Longstreet's position on Marye's Heights – all were repulsed with heavy losses. On December 15, Burnside withdrew his army, ending another failed Union campaign in the Eastern Theater.

The South erupted in jubilation over its great victory. The Richmond Examiner described it as a "stunning defeat to the invader, a splendid victory to the defender of the sacred soil." Reactions were opposite in the North, and both the Army and President Lincoln came under strong attacks from politicians and the press. Senator Zachariah Chandler, a Radical Republican, wrote, "The President is a weak man, too weak for the occasion, and those fool or traitor generals are wasting time and yet more precious blood in indecisive battles and delays."