The Siege of Vicksburg, which lasted from May 18 to July 4, 1863, was significant in the American Civil War as it gave the Union control of the Mississippi River. This victory for Union General Ulysses S. Grant effectively bisected the Confederacy, disrupting their supply lines and communication. The fall of Vicksburg boosted Northern morale and was pivotal in the overall strategy of the Union to weaken Confederate forces. It also marked a turning point in the war, emphasizing the importance of military strategy and control over critical geographical locations for achieving victory.