The battle that followed shortly after Antietam was the Battle of Fredericksburg.

Fought from December 11 to December 15, 1862, this battle occurred as Union General Ambrose Burnside sought to capitalize on the momentum from Antietam. However, Burnside faced significant challenges, including logistical issues and poor weather. The Union forces encountered strong defenses from Confederate General Robert E. Lee's troops positioned on high ground overlooking the town of Fredericksburg, Virginia. The resulting confrontation was disastrous for the Union, leading to heavy casualties and a decisive Confederate victory, further complicating the Union's military objectives in the war.