Which battle is remembered for its one-sided nature and high Union casualties?

The Battle of Fredericksburg, fought in December 1862, is noted for its one-sided nature and the significant casualties suffered by Union forces. During this battle, the Union, led by General Ambrose Burnside, launched multiple assaults against well-entrenched Confederate positions on Marye's Heights. The Confederate troops, commanded by General Robert E. Lee, were able to effectively defend their positions, resulting in heavy Union losses, with approximately 12,600 Union soldiers killed, wounded, or missing, compared to around 5,000 Confederate casualties.

The disastrous outcome for the Union at Fredericksburg starkly highlighted the challenges faced by Union leadership and the difficulties of frontal assaults against fortified positions. This battle is often cited as a clear example of the high costs involved in the Civil War, especially for Union forces.

Other battles listed, such as Gettysburg, Antietam, and Bull Run, while also significant, do not represent the same degree of one-sidedness in terms of casualties, especially with Gettysburg being noted for its Union victory and Antietam recognized for being tactically inconclusive but strategically beneficial to the Union. Bull Run was marked by significant confusion and a breakdown in Union command rather than a simple one-sided defeat