Which battle is recognized as one of the significant conflicts where Union forces halted the Confederate advance into Maryland?

The Battle of Antietam is recognized as a pivotal conflict during the American Civil War where Union forces successfully halted the Confederate advance into Maryland. Fought on September 17, 1862, it marked the bloodiest single day in American history, with significant casualties on both sides. The outcome was strategically important for the Union, as it not only halted Robert E. Lee's plans to move north but also provided President Abraham Lincoln with the opportunity to issue the Emancipation Proclamation shortly afterward. This battle shifted the momentum of the war in favor of the Union and is often credited with revitalizing the Northern cause.

The other battles listed, while significant in their own right, do not correspond to this specific context of halting a Confederate advance into Maryland. Gettysburg, while a crucial turning point, occurred later and focused on preventing Confederate forces from invading Pennsylvania. The battles of Shiloh and Bull Run were essential earlier confrontations, but they did not involve the specific geographical and strategic situation presented in the question regarding Maryland.