The Civil War crater that swallowed 4,000 Union soldiers at Petersburg

The Great Crater That Doomed Union Forces

Petersburg National Battlefield preserves the site where Pennsylvania coal miners pulled off an incredible feat of engineering that became a military disaster.

In 1864, Lieutenant Colonel Henry Pleasants convinced his superiors to let his Schuylkill County miners dig a 510-foot tunnel under Confederate lines.

They worked around the clock for weeks, packed it with 8,000 pounds of gunpowder, and created a massive crater that killed 352 Confederates instantly.

But Union troops charged into the crater instead of around it, turning brilliant engineering into Grant’s “saddest affair.”

Here’s how the most ambitious tunnel operation of the Civil War went so terribly wrong.

Coal Miners Came Up With a Crazy Plan to Blow Up Confederate Lines

Lieutenant Colonel Henry Pleasants of the 48th Pennsylvania Infantry spotted a chance when looking at the Confederate Elliott’s Salient.

His regiment, full of Schuylkill County coal miners, was just 100 yards from enemy lines at Petersburg in June 1864.

One of his men looked from his trench and said, “We could blow that damned fort to bits if we dug a mine shaft under it. ” Army engineers laughed at the idea as “nonsense.”

They said a tunnel over 400 feet long wouldn’t work without proper air flow. Even Grant and Meade thought it was just busy work to keep soldiers busy.

Meade never officially approved the project, so Chief Engineer Duane refused to give the 48th the tools, wood, wheelbarrows, and sandbags they needed.

These Guys Started Digging With Homemade Tools From Cracker Boxes

Work started at noon on June 25, 1864, but the miners lacked proper tools. They changed army picks to make them work better.

For wood, they first tore down a rebel bridge, then got supplies from a sawmill five or six miles away. The miners carried dirt out in handmade carriers built from cracker boxes with handles.

They lined the tunnel walls, floor, and ceiling with wood taken from an unused mill nearby. Pleasants and his coal miners used their work skills to fix one problem after another.

They worked in shifts day and night, making good progress despite no official help or proper mining tools.

A Cave-In Almost Ruined Everything On July 2nd

The tunnel moved ahead quickly until July 2, when they hit very wet ground.

The wooden supports gave way and the tunnel nearly closed as the roof and floor almost met in the middle. After this problem, they had to dig through sticky clay-like soil, which slowed them down a lot.

The Pennsylvania miners used their coal mining know-how to fix the collapsed section with new wood supports. They started digging again despite the cave-in that could have ended the whole plan.

This close call showed the dangers the miners faced every day as they dug deeper under Confederate lines.

A Simple Canvas Door Solved Their Biggest Problem

Fresh air for tunnel workers became the main challenge. About 100 feet into the mine, Pleasants had his men dig a vertical air shaft.

They put a canvas door across the mine entrance and ran a wooden air pipe the entire length of the tunnel. A canvas divider kept the miners’ air supply separate while letting workers move in and out easily.

“Regular Army know-it-alls said it couldn’t work, that I couldn’t move air that far without digging to the surface… but I did it,” Pleasants later bragged.

This clever setup meant they didn’t need extra air shafts that Confederate lookouts might spot. The simple but effective system kept fresh air flowing to where men worked in tight spaces.

The Miners Finished A 511-Foot Tunnel In Just Three Weeks

Pleasants and his 400 men finished the main shaft by July 17, an amazing mining feat done in just three weeks.

The tunnel stretched 511 feet, starting in a low area downhill and more than 50 feet below the Confederate battery. The mine formed a “T” shape.

The main tunnel was 511 feet long, with side passages added at the end. The tunnel stood about 5 feet high, 54 inches wide at the bottom, and 2 feet wide at the top.

By July 16, miners began digging side tunnels under the Salient.

The Pennsylvania coal miners cut and set up all their own wood, made working drainage systems, and built air flow that worked perfectly, despite what West Point engineers claimed was impossible.

Confederate Soldiers Heard Digging But Looked In The Wrong Places

Confederate troops heard picks and shovels twenty feet below them and dug “listening shafts” to find the noise.

Lee heard rumors about Union mining but ignored them for two weeks before starting weak counter-digging attempts.

Officers Stephen Elliott and Richard Pegram, who led the Salient, told their men to dig vertical shafts with counter-mines, worried about what might be happening underground.

Pleasants learned about these Confederate efforts and changed his tunnels’ direction and depth to avoid being found. The Confederates never found the Union mine.

When the digging noises stopped on July 23, they quit looking, a mistake that would cost many lives. The Pennsylvania miners had finished their tunnel right under enemy lines without being caught.

Four Tons Of Black Powder Got Packed Under Confederate Lines

Around Thursday, July 28, the Pennsylvania miners started loading the tunnel with explosives. They packed in 320 twenty-five-pound kegs of black powder, adding up to four tons.

Pleasants asked for six tons, but even with four, the planned blast would be the largest man-made explosion in the Western Hemisphere up to that time.

Workers carefully placed the powder in the side tunnels to cause maximum damage along the Confederate defense line.

The miners positioned the explosives to create the biggest possible hole in the Confederate fortifications. Each keg connected to a complex fuse system designed to set off all charges at once.

The Fuse Fizzled Out At The Worst Possible Time

Henry Pleasants lit the fuse at 3:15 AM on July 30, 1864. The explosion was set for 3:30 AM, but that time passed with no blast.

The Union troops waiting to attack grew restless as minutes went by. The miners got poor-quality fuses they had to piece together themselves.

These makeshift fuses burned out before reaching the powder.

By four o’clock, General Meade grew worried and sent Burnside a message: “The commanding general orders that if your mine has failed that you attack at once.”

The whole operation hung in the balance as dawn came closer.

Union troops sat exposed in their staging areas, and the surprise factor was slipping away with each passing minute.

Two Brave Miners Crawled Into A Potential Death Trap

Two volunteers from the 48th Regiment stepped up to fix the problem.

Lieutenant Jacob Douty and Sergeant Harry Reese crawled into the tunnel that could have blown up any second. Born in Wales in 1835, Henry Reese worked in Pennsylvania coal mines before the war.

He led the way with a lamp while Douty followed. Douty used his pocket knife to fix the broken fuse they found about halfway to the powder charge.

Reese later said, “I didn’t stop to feel, I had been in tight spots in coal mines before the war didn’t mind this job.”

After they got out, he admitted, “When I got outside, and stood looking toward the fort that was doomed, I felt something then trickling near my eyes.”

The Explosion Created A Massive Crater That Still Exists Today

At 4:44 AM, the charges finally exploded in a huge blast.

A newspaper writer wrote, “Clods of earth weighing at least a ton, and cannon, and human forms, and gun-carriages, and small arms were all clearly seen shooting upward in that fountain of horror.”

The explosion created a crater 170 feet long, 100 to 120 feet wide, and at least 30 feet deep. This crater remains visible at the Petersburg battlefield today.

The blast killed 352 Confederate soldiers instantly.

One witness described the scene: “There was a heavy jar, a dull thud, a big volcano-puff of smoke and dust, and up went the earth under and around that fort for a distance in the air of a hundred feet or more, carrying with it cannons, caissons, muskets—and men.”

The Perfect Plan Turned Into A Perfect Disaster

General Ledlie’s men struggled to climb out of their own trenches, then moved forward into chaos and horror.

Confused by contradictory orders and poor leadership, the Union troops failed to either widen the breach or rush toward the high ground at Blandford Church.

Instead, many Union soldiers jumped into the crater or froze in positions around it. They became easy targets for Confederate troops who quickly reorganized.

The battle ended with 4,000 Union casualties compared to only 1,800 Confederate losses. Grant later called it “the saddest affair I have witnessed in this war.”

Sergeant Henry Reese, who had risked his life to relight the fuse, later reflected, “If I had known what a blunder it would be, I never would have gone in to relight the fuse.”

The miners’ engineering triumph had become a military catastrophe.

Visiting Petersburg National Battlefield

Petersburg National Battlefield at 5001 Siege Road in Petersburg, Virginia tells the story of Pennsylvania coal miners who dug a 510-foot tunnel to blow up Confederate lines but failed badly.

You can visit for free and see exhibits at the Eastern Front Visitor Center, including an original hardtack box used to carry tunnel dirt.

Take the self-guided driving tour to The Crater battlefield or walk trails that follow the mine shaft path to Elliott’s Salient.

This article was created with AI assistance and human editing.

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