Final answer:
The siege of Vicksburg was a pivotal moment in the Civil War, leading to Union control over the Mississippi River, splitting the Confederacy, and highlighting Grant's leadership.
Step-by-step explanation:
The siege of Vicksburg was a crucial turning point in the Civil War because it gave the Union complete control over the Mississippi River, effectively bisecting the Confederacy and disrupting their supply lines and communication. This victory, achieved by Union forces under the command of Major General Ulysses S. Grant, was the culmination of a well-orchestrated siege, which involved encircling the city, cutting off supplies, and employing siege tactics that minimized Union casualties while maximizing pressure on the Confederate defenders. Additionally, the fall of Vicksburg had significant strategic implications as it prevented Confederate forces in the Western Theatre from launching strong offensives and showcased Grant's military prowess, which caught President Abraham Lincoln's attention and contributed to Grant's eventual promotion to command all Union armies.