Vicksburg, Siege of, May 19–July 4, 1863, a decisive campaign of the American Civil War. The fall of Vicksburg on July 4, followed a few days later by the capture of Port Hudson, Louisiana, gave control of the Mississippi River to the Union and cut the Confederacy in two.

In April, 1862, Captain David G. Farragut, of the Union Navy, captured New Orleans; he then moved his ships up the river. In July he was joined near Vicksburg, Mississippi, by Captain Charles H. Davis. The combined squadrons bombarded the city but inflicted only light losses on the Confederate defenders.

In the fall and winter General U. S. Grant, assisted by ironclads and gunboats under acting Rear Admiral David Dixon Porter, made several attempts to take the city from the east. The first attempt was blocked when the Holly Springs supply base was destroyed by raiders and General W. T. Sherman's assault on Chickasaw Bayou was blocked. Grant then decided to attack from the south, but an advance across the swampy terrain was impossible because of winter rains. Sailing the troops down the river past Vicksburg's formidable guns was too risky, so Grant tried to bypass the city by digging canals, but the project proved impractical.

By late March, the winter rains had ceased and the land was dry enough for Grant to attempt an overland march; he moved his army down the west bank of the river, bringing it into position to cross south of Vicksburg. Porter's fleet sailed past the Vicksburg guns and transported the troops across the river at Bruinsburg. After a victory at Port Gibson on May 1, Grant cut loose from his base of supplies and moved between the forces of General John C. Pemberton defending Vicksburg and reinforcements under General Joseph E. Johnston.

Fights at Raymond on May 12 and at Jackson on May 14 drove off Johnston. Grant then turned on Pemberton and at Champion's Hill on May 16 and Big Black River on May 17, drove the Confederates into Vicksburg. Assaults on May 19 and 22 failed. The siege lasted 47 days. The defenders made bread of ground peas and ate mule meat. On July 4, 1863, the day after the Union victory at Gettysburg, Pemberton surrendered.