The Armies rarely fought battles in wintertime. But Union General Ambrose Burnside had delayed any attack at Fredericksburg, Virginia for nearly two months while he waited for engineers to construct pontoon bridges across the Rappahannock River, which runs through the city. Fredericksburg was a key Confederate possession, located halfway between Washington, D. C. and their Capitol in Richmond. Burnside's delay enabled General Lee and his subordinate commanders Stonewall Jackson and James Longstreet to fortify the heights above the city into an impregnable position. Nevertheless, Burnside tried to take the heights 9 times on December 13, only to be beaten back.

On the night of the 13, there was a spectacular display of Northern Lights (Aurora Borealis) in the sky, a sight rarely seen so far South. Some soldiers took the display as an omen. Perhaps the heavens were celebrating this Southern Victory … or perhaps mourning in a spooky way the dreadful casualties the Union Army had suffered that day.

The men of the 20th Maine also claimed to be the last to leave the field, but in the darkness and confusion it might have been difficult to be certain.