Which battle was notable for being a precursor to a decisive shift in the American Civil War?

The Battle of Antietam, fought on September 17, 1862, is often recognized as a significant turning point in the American Civil War due to its immediate and far-reaching consequences. It is notable for being the bloodiest single-day battle in American history, with around 22,000 casualties.

One of the most crucial outcomes of the battle was its impact on the Union's moral standing and strategic goals. The tactical stalemate allowed President Abraham Lincoln to issue the Emancipation Proclamation shortly afterward, which declared the freedom of slaves in the Confederate states. This not only shifted the war's focus toward the abolition of slavery but also prevented potential European intervention on behalf of the Confederacy, as many European powers were anti-slavery.

Furthermore, the battle bolstered Union morale and demonstrated that the Confederacy could be stopped. This shift in momentum was essential in the following campaigns and helped lay the groundwork for future Union victories. Overall, the Battle of Antietam represented a crucial juncture in the conflict, leading to significant political and military changes that would influence the course of the war.