The day Lewis and Clark ditched mapmaking to hunt 18-inch demons in South Dakota

Lewis and Clark’s Devil Hunt at Spirit Mound

On August 25, 1804, Lewis and Clark took on a quest that had nothing to do with mapping rivers. They hiked nine miles in brutal heat to find tiny devils.

Native tribes swore that 18-inch spirits with big heads lived on a 70-foot hill, armed with deadly arrows that had killed three Omaha men.

The captains picked ten men, including York, and set out at 8 AM from the Vermillion River. The heat hit hard.

Even Lewis’s dog Seaman fell down, and the men got so thirsty they had to rush to a creek. At the top, they found no devils—just swarms of ants and gentle birds.

Spirit Mound still stands in South Dakota, where you can walk the same trail these brave men once did.

Tiny Devils Scared Local Tribes with Magic Arrows

The Omaha, Sioux, and Otoe tribes feared a 70-foot hill they thought housed small beings with big powers. These little devils stood just 18 inches tall but had huge heads and deadly weapons.

Local tribes warned Lewis and Clark about these spirits who could kill from far away with magic arrows. Tribal elders told them that three Omaha warriors recently died after getting too close to this sacred place.

Native Americans completely stayed away from the hill.

Jefferson Wanted Answers About Prairie Spirits

Lewis and Clark took their science mission seriously, including checking out local ghost stories. President Jefferson told them to write down Native American beliefs and customs during their trip west.

The captains saw Spirit Mound as a chance to test local legends against what they could see with their own eyes. They decided to visit the haunted hill themselves rather than just listen to stories.

The Captains Picked Their Best Men for the Devil Hunt

On August 25, 1804, Lewis and Clark chose ten men to join their ghost-hunting group.

The team included their most trusted people: Sergeant Ordway, hunter John Shields, explorer Joseph Fields, and John Colter. William Bratton and York, Clark’s slave, also came along.

The group left their main camp at the mouth of the Vermillion River by 8 AM, ready to solve the mystery of the deadly spirits.

The Prairie Turned Into an Oven That Morning

They first walked across open grasslands with no trees for shade. After four miles, they crossed White Stone Creek, which gave them a quick chance to cool off.

The August sun beat down hard as they kept walking across the open prairie. With each hour, the heat got worse, making the flat land feel like a trap.

The men kept moving despite feeling hot and tired.

Even Lewis’s Dog Couldn’t Handle the Heat

The hot weather hurt everyone, including Lewis’s Newfoundland dog, Seaman. The big dog fell down from heat stroke and couldn’t keep going.

Someone took him back to White Stone Creek so he could drink and cool off in the water. Clark wrote that Lewis was "much fatigued from heat" as they walked on.

Several men said they felt very thirsty as sweat soaked their clothes.

They Reached the Top But Nearly Passed Out

Around noon, the tired group finally made it to the top of Spirit Mound. The nine-mile walk in awful heat left them dizzy, thirsty, and barely able to function.

Their water was almost gone, making it hard to think clearly. Despite feeling terrible, the captains still tried to look around the hill.

They searched for any sign of the tiny devils but worried more about staying alive than finding ghosts.

The Men Made a Desperate Run for Water

Things got so bad they had to stop looking and make an emergency trip for water. The group walked three miles northeast to reach White Stone Creek, where they could finally drink.

This unplanned stop showed how much they underestimated the August heat on the open prairie. Clark wrote that several men almost collapsed before they reached the creek.

Only after drinking could they get back to their work.

Flying Ants and Birds Explained the "Devils"

Instead of finding tiny warriors with arrows, they found something normal. Huge swarms of flying ants covered parts of the hill, blown there by prairie winds.

These bugs attracted big flocks of swallows and martins that ate them. The birds showed no fear of humans, staying put until the men came within a few feet.

This natural event likely explained what local tribes thought was ghost activity, with swirling bird flocks looking strange from far away.

Buffalo Herds Stretched Beyond the Horizon

From their high spot, Lewis and Clark saw something amazing that made their suffering worth it. Huge herds of buffalo and elk filled the surrounding prairies in all directions.

Clark tried to count them, guessing more than 800 animals visible at once. The captains watched these massive herds move across the grasslands below them.

This wide view showed them the region’s wildlife in a way they couldn’t see from ground level.

Both Captains Wrote Everything Down

True to their job, Lewis and Clark carefully wrote about their Spirit Mound trip in their journals.

They described the hill’s size and shape, the land around it, and the natural reason for what locals thought were spirits.

Their notes included the exact time they reached each point, how far they traveled, and what animals they saw. These detailed records turned a local legend into written scientific facts.

You Can Visit the Same Hill Today

Spirit Mound still stands near Vermillion, South Dakota, looking much like it did when Lewis and Clark climbed it in 1804.

The site has been preserved as Spirit Mound Historic Prairie, allowing visitors to walk the same path the explorers took.

Unlike the expedition members, today’s tourists can drive close to the hill and follow a well-marked trail to the top.

The location serves as a physical connection between Native American cultural history and the scientific journey of the Corps of Discovery, marking an important stop on their famous westward trek.

Visiting Vermillion, South Dakota

Spirit Mound Prairie is at 31148 SD Highway 19, about 5 miles north of Vermillion.

You can visit this 320-acre prairie restoration for free year-round and walk the same trail Lewis and Clark took on August 25, 1804.

The interpretive signs explain Native American legends about tiny spirits who supposedly killed intruders. From the summit, you’ll see the same prairie views the Corps of Discovery saw over 200 years ago.

This article was created with AI assistance and human editing.

Read more from this brand:

• Washūŋ Niya: The sacred cave where the first Lakota people entered Earth
• South Dakota’s most mind-blowing attraction isn’t Rushmore—it’s underground
• The last Lakota ghost dance before Wounded Knee