When people ask when did the battle of vicksburg occur, they usually want a quick date to plug into a history quiz. May 18 to July 4, 1863. There you go. But honestly? That answer is kinda misleading. If you only look at those six weeks, you miss the actual "war" part of the Vicksburg story. History isn't just a series of isolated events; it’s a messy, muddy, multi-year headache that almost broke the Union’s spirit before Ulysses S. Grant finally cracked the nut.
Vicksburg wasn't just a battle. It was a siege. It was a campaign. It was a nightmare for everyone involved.
To really understand the timeline, you have to look at the winter of 1862. That’s when the real trouble started. The Union knew that if they didn't take this specific high ground in Mississippi, the Confederacy would keep using the river to move supplies. Abraham Lincoln famously called Vicksburg the "key" to the whole war. He wasn't exaggerating. Without it, the South stayed whole. With it, the Confederacy was sliced right down the middle, separating the vital resources of Texas, Arkansas, and Louisiana from the rest of the rebellion.
The Long Road to May 1863
Grant didn't just wake up in May and decide to surround the city. He’d been failing at it for months. During the winter of 1862 and the early spring of 1863, the Union army tried all sorts of wild engineering projects. They tried digging a canal to bypass the city's big guns. It flooded. They tried moving through the bayous. They got stuck in the mud and harassed by snipers. It looked like a disaster.
People in Washington were calling for Grant to be fired. They thought he was a drunk and a failure. But Grant had this weird, quiet persistence. On April 16, 1863, the timeline shifted dramatically. Admiral David Dixon Porter ran his gunboats and supply ships past the Vicksburg batteries under the cover of night. It was a gamble that changed everything.
By late April, Grant’s troops were marching down the west side of the Mississippi River in Louisiana. They crossed over into Mississippi at Bruinsburg on April 30. This move is what military historians like James M. McPherson often point to as one of the most brilliant maneuvers in modern warfare. Grant cut himself off from his own supply lines. He lived off the land. He fought and won five separate battles in just 17 days: Port Gibson, Raymond, Jackson, Champion Hill, and Big Black River Bridge.
✨ Don't miss: Ukraine War Map May 2025: Why the Frontlines Aren't Moving Like You Think
It was a whirlwind. By the time the Confederate General John C. Pemberton retreated into the Vicksburg defenses, he was demoralized and outnumbered.
The Siege Begins: May 18 to July 4, 1863
So, when did the battle of vicksburg occur in its most intense form? The formal Siege of Vicksburg officially kicked off on May 18, 1863.
Grant tried to end it quickly. He ordered massive assaults on May 19 and May 22. He thought the Confederates were too broken to hold. He was wrong. The Union soldiers charged up steep ravines into a wall of lead. They were slaughtered. After losing thousands of men in just a few hours, Grant realized he couldn't take the city by force. He had to starve them out.
For 47 days, the city was under constant bombardment.
Imagine living in a hole in the ground. That’s what the civilians did. Because the Union Navy was shelling from the river and the Army was shelling from the land, the people of Vicksburg dug caves into the yellow clay hills. They called it "Prairie Dog Village." Iron shells rained down day and night. Food ran out. People started eating horses, mules, and eventually—according to some accounts—dogs and rats. It was a slow-motion catastrophe.
🔗 Read more: Percentage of Women That Voted for Trump: What Really Happened
Living in the Caves
The conditions were horrific. It wasn't just the hunger. It was the smell of decaying animals, the heat of a Mississippi summer, and the constant fear that your cave might collapse from a direct hit. You’ve got to feel for the non-combatants who were caught in a geopolitical vise.
The Mines
Union soldiers got creative too. They dug tunnels under the Confederate lines, packed them with gunpowder, and blew them up. The most famous "crater" happened on June 25. The explosion was massive, but the following infantry charge failed to break through. It just became another bloody stalemate in the dirt.
Why July 4 Was the Final Straw
By early July, Pemberton knew no help was coming. General Joseph E. Johnston was supposedly nearby with a relief army, but he never made a move. Pemberton asked Grant for terms on July 3.
The timing was symbolic and painful. Pemberton chose to surrender on July 4, 1863, hoping he’d get better terms from the Union on their Independence Day. It worked, mostly. Grant paroled the Confederate prisoners rather than sending them to Northern prison camps, mainly because he didn't want to feed them or transport them.
The news of the Vicksburg surrender reached Washington just as the news of the victory at Gettysburg arrived. It was the turning point. The Confederacy was split. The Mississippi River was a "Union highway" once again.
💡 You might also like: What Category Was Harvey? The Surprising Truth Behind the Number
Interestingly, the city of Vicksburg didn't officially celebrate the Fourth of July for another 81 years. The scars of the siege ran that deep. It wasn't until 1944, during World War II, that the city really brought the holiday back into the fold.
Timeline Summary
If you need the breakdown for a project or just to keep the facts straight in your head, here’s how the dates actually shake out:
- December 1862: Initial Union attempts to take the city (Battle of Chickasaw Bayou).
- January – March 1863: The "Bayou Expeditions" and canal digging (mostly failures).
- April 16, 1863: Porter’s fleet runs the Vicksburg batteries.
- April 30, 1863: Grant’s army crosses the Mississippi River at Bruinsburg.
- May 1 – May 17, 1863: The Inland Campaign (battles at Raymond, Jackson, and Champion Hill).
- May 18, 1863: The Siege of Vicksburg officially begins.
- May 19 & 22, 1863: Major Union assaults fail with high casualties.
- July 4, 1863: Confederate surrender.
Beyond the Dates: Why It Matters Now
Understanding when did the battle of vicksburg occur helps place the American Civil War in its proper context. It wasn't just about the Eastern Theater or Robert E. Lee. The war was won in the West. When Vicksburg fell, the Confederacy lost its ability to function as a unified nation.
If you’re planning to dive deeper into this, don't just read the dry military reports. Look for the memoirs of the people who were there. "My Cave Life in Vicksburg" by Mary Ann Loughborough is a wild read if you want to know what it was like to be a civilian during the shelling. For the military side, Grant’s own memoirs are surprisingly readable and honest about his mistakes.
The Vicksburg National Military Park today is one of the most densely monumented battlefields in the world. It’s haunting. You can see the actual USS Cairo, a Union ironclad that was sunk by a "torpedo" (a 19th-century mine) and recovered from the river mud a century later.
Actionable Next Steps for History Buffs
To truly grasp the scale of what happened in 1863, you should move beyond the dates and engage with the geography and the primary sources:
- Visit the Battlefield Virtually or in Person: If you can't get to Mississippi, the National Park Service website has incredible 3D maps that show the "loop" of the river as it existed in 1863. The river has actually changed course since then.
- Compare with Gettysburg: Research the "Double Victory" of July 1863. See how the loss of Vicksburg affected the Confederate economy compared to the tactical loss at Gettysburg.
- Read the Soldiers’ Letters: Use the Library of Congress digital archives to find letters from the 13th Infantry or the 4th Mississippi. The contrast in their daily lives during the siege is striking.
- Track the Logistics: Look at how Grant fed 70,000 men while deep in enemy territory. It’s a masterclass in logistics that is still studied at West Point today.
The Battle of Vicksburg wasn't a single day of glory. It was a grueling, agonizing 47-day test of will that ended on a hot July morning, changing the trajectory of American history forever.