On November 7, 1862, Major General Ambrose Everett Burnside received orders to do something he had previously twice
declined to do. No longer allowed such soldierly discretion, the President now ordered him to assume command of the Union Army of the
Potomac. His friend and former commander, and perhaps the most popular commanding general the Army of the Potomac would ever have, Major
General George B. McClellan would be sent home to New Jersey to "await further orders" that would never come.
General Burnside, aware of President Lincoln's criticism of his predecessors' perceived slowness to action, would quickly devise a plan
to outmaneuver the Southern Army by crossing the Rappahannock at Fredericksburg to threaten the Confederate Capital at Richmond.
However, Burnside knew the road would not be easy. On November 10, 1862, Union General Franz Sigel would write to Burnside, "A
sergeant, who escaped from Fredericksburg, reports the bridges over the Rappahannock gone." On the 13th, Sigel would follow with,
"There are no bridges across the Rappahannock, the Potomac and Accokeek Creeks, as stated in former report, all these bridges
having been destroyed." 
The Union commander would place emphasis on the speed of the Army of the Potomac and the building of the crucial pontoon bridges across
the Rappahannock River. Out marching General Lee would allow the bluecoats to have the inside track towards Richmond. General Lee, in
Burnside's mind, would have no choice but to leave his fortifications and face a much larger army in the open.
Although Burnside's men began arriving along the banks of the Rappahannock on November 17, General Lee and his men would arrive to
defend the Fredericksburg side of the river a week before the pontoons. This delay would allow the southerners to establish and
fortify their defensive lines making the Union's chances to maneuver appear exceedingly grim.
The above image pictures a section of a pontoon bridge recreated on the grounds of Chatham Manor, Major General Edwin Vose Sumner's
headquarters during the battle. This reconstructed pontoon is 80% of what would have been the actual size during the battle.