Ulysses S. Grant is known as the "Hero of Vicksburg" for his pivotal role in the Siege of Vicksburg, which lasted from May 18 to July 4, 1863.

Grant's successful campaign culminated in the Union's capture of the fortified city, a strategic stronghold on the Mississippi River. This victory effectively split the Confederacy in two and gave the Union complete control of the river, significantly boosting Northern morale. Grant's leadership and strategic prowess during this campaign elevated his reputation and set the stage for his later promotion to Commanding General of the Union Army.