Ambrose Burnside was still commander of the Army of the Potomac. Lincoln contemplated removing him, but no better alternative had yet presented itself. Knowing that he was the laughingstock of many of his generals, and that the men of the army had lost their friendly feeling for him, Burnside made one last attempt. On January 21, 1863, he had a large section of the Army of the Potomac march upriver from Fredericksburg, planning to cross the Rappahannock with five pontoon bridges.

Lee had only the dimmest idea of what was in process, but the weather came to his aid. The morning of January 21 was fine, and the afternoon was not too bad, but a thunderous rainstorm set in that evening and just did not quit. When the federal troops set fires the next morning, the green wood they used turned smoldering fires into thick banks of smoke. Under normal conditions, these setbacks would have been considered par for the course. But the Army of the Potomac was not in a normal frame of mind. The Battle of Fredericksburg had unhinged it.