Which battle was pivotal for Union control of the Mississippi River?

The Battle of Vicksburg was pivotal for Union control of the Mississippi River because it effectively split the Confederacy in two and gave the Union a significant strategic advantage. The Union's victory at Vicksburg, which took place from May 18 to July 4, 1863, allowed them to control the entire length of the Mississippi River. This control was essential for the movement of troops and supplies, as it opened up a vital transportation route and disrupted Confederate communications and logistics.

Under the command of General Ulysses S. Grant, the Union forces besieged the city, cutting off supplies and reinforcements to the Confederate defenders. The surrender of Vicksburg on July 4, 1863, not only marked a turning point in the war by bolstering Northern morale but also sealed the fate of the Confederacy’s ability to operate effectively in the western theatre.

The other battles mentioned did not focus on control of the Mississippi River to the same extent. The Battle of Gettysburg, while significant as a turning point in the Eastern Theatre of the Civil War, dealt primarily with the Confederate Army's invasion of the North. The Battle of Antietam is notable for being one of the bloodiest single-day battles