As the Civil War began, the South controlled the Mississippi River—a critical transportation corridor and supply line—from Cairo, Illinois, all the way down to the Gulf of Mexico. Vicksburg, given its strategic location on the east bank of the Mississippi River, was “the nailhead that holds the South’s two halves together,” according to Confederate President Jefferson Davis.

The Vicksburg campaign was one of the Union Army’s most successful endeavors in the Civil War—it was also one of the longest. Although the first attempt by General Ulysses S. Grant to take the city failed in the winter of 1862-63, he renewed his efforts in the spring.

Union Admiral David Porter had run his flotilla past the Vicksburg defenses in early May as Grant marched his army down the west bank of the river opposite Vicksburg, crossed over back into Mississippi and drove toward Jackson, the state capitol. After defeating a Confederate force near Jackson, Grant turned his troops back to Vicksburg.

On May 16, Grant defeated a force under General John C. Pemberton at Champion Hill, one of the Confederates’ last defenses outside of Vicksburg. Pemberton retreated back to Vicksburg, and Grant sealed off the city by the end of May. In three weeks time, Grant’s men had marched 180 miles, won five battles and captured some 6,000 prisoners.

Grant made some attacks after bottling Vicksburg but found the Confederates well entrenched. Starting on May 18, preparing for a long Siege of Vicksburg, Grant's army constructed 15 miles of trenches and enclosed Pemberton’s force of 29,000 men inside the perimeter. It was only a matter of time before Grant, with 70,000 troops, captured Vicksburg.

Confederate attempts to rescue Pemberton and his force failed from both the east and west, and conditions for both military personnel and civilians in Vicksburg deteriorated rapidly. Many residents—cut off from all supplies and rapidly running out of food—moved to tunnels dug from the hillsides to escape the constant bombardments.

After holding out for 47 days, Pemberton surrendered on July 4, 1863—Independence Day—and President Abraham Lincoln wrote that the Mississippi River “again goes unvexed to the sea.”

The Confederate defeat at Vicksburg, and a second Union victory downriver at Port Hudson, Louisiana, ensured that the Union would have complete control of the Mississippi River. Lincoln reportedly referred to the successful Vicksburg campaign as "the key to the war."

Today, the Battle of Vicksburg and the siege are commemorated at the Vicksburg National Military Park. The town of Vicksburg—which had suffered miserably during the siege, with disease, starvation and death stalking soldier and civilian alike—would not celebrate the Fourth of July for 81 years.

Vicksburg: History & Culture. National Park Service.
The Battle of Vicksburg. Smithsonian National Museum of American History.
Siege of Vicksburg. U.S. Army Heritage and Education Center.