In the fall of 1862, at the end of the Maryland Campaign, the Union and Confederate armies in the Eastern Theater were worn out. From the end of June through September, the opposing sides had fought some twenty engagements in three campaigns and inflicted more than 100,000 casualties on each other. The pace was unsustainable and both sides took time to rest and refit.
For not pursuing General Robert E. Lee fast enough after Antietam, President Abraham Lincoln removed Maj. Gen. George B. McClellan from command on November 7, and his replacement, Maj. Gen. Ambrose E. Burnside, quickly implemented a new plan of advance. Burnside’s plan was a good one and initially was well executed. He feinted toward Gordonsville to draw Lee away from his real goal of crossing the Rappahannock River at Fredericksburg, placing his army between Lee and Richmond. The Federals surprised Lee by covering 35 miles to the southeast in three days. Upon reaching the Rappahannock, however, the plan fell apart. Burnside needed pontoon bridges to cross the river, but the wagons carrying them failed to arrive due to bureaucratic delays. Heavy rains flooded the river and contributed to the long wait. The delay gave Lee time to concentrate along the heights west of Fredericksburg.
Despite the obvious strength of Lee’s defensive position, Burnside crossed the Rappahannock on the late-arriving pontoons and occupied Fredericksburg on December 11. On December 13, he attacked Lee’s army west and south of the town. Despite a brief breakthrough, the Battle of Fredericksburg was a disaster for Federal forces. More than 12,000 Union soldiers became casualties without gaining any ground, while Lee suffered fewer than half as many. On December 15, Burnside retreated across the Rappahannock ending the active campaigning of 1862 in the Eastern Theater.