The Battle of Vicksburg took place between May 18 - July 4, 1863 in Vicksburg, Mississippi. The Union fought under Major General Ulysses S. Grant with 77,000 men. The Confederacy was led by Lieutenant General John C. Pemberton with 33,000 men. This victory for Union soldiers effectively severed the Trans-Mississippi West theater from the remainder of the Confederacy and cemented support in the Midwest for the Union cause.
taken from - Spencer C. Tucker, Battles that Changed American History (Santa Barbara: ABC-CLIO, 2014): 149-152.