Union soldiers retreat from Balls Bluff near Leesburg. Many were killed by Confederates firing down on them as they tried to cross the Potomac. (Courtesy of "The Civil War in America from the Illustrated London News")

Imagine this. It’s October 1861, and Union soldiers are camped 35 miles upstream from Washington along the Potomac River’s Maryland shore and on Harrison’s Island. They are on picket duty, making sure no Confederates cross over from Virginia. Opposite them, Confederate pickets guard the Virginia shore. Sometimes the young soldiers fire at one another across the river. Sometimes they break the rules and wade out in the shallow places to talk.

Then one night, 20 Union men from the island pile into a boat, row to the Virginia shore and struggle up a steep path to the top of a bluff. They cross a large clearing and follow a path through the woods, hoping they won’t be shot or captured. Hearts beat fast. Mouths are dry.

What are they doing in enemy territory? Their orders are to find out if the Confederates have left the area around Leesburg. Wait! What’s that in the moonlit field? A row of tents? That means the rebels are still here.

A terrible mistake

Confederates were nearby, but what looked like tents in the darkness was a row of trees. And that trick of the eye set the stage for the Union defeat in the Battle of Ball’s Bluff.

Here’s what happened:

The scouts hurried back to report that they had found a small enemy camp, and a raiding party was immediately sent to attack it. But with three small boats, it took four hours for 300 men to cross from the island to the base of the bluff. When they finally reached the “camp,” it was light enough to see the trees that had looked like tents the night before.

If the raiding party had returned to the island, the day would have had a different ending. Instead, the men waited while messages were carried back and forth to their general’s headquarters in Maryland. While they waited, they were discovered by the Confederates — a small group at first, but then more of them. After hours of minor fighting, the outnumbered raiding party headed back to the bluff.

Meanwhile, hundreds more Union soldiers had crossed the river and waited in the clearing on top of the bluff. Confederates arrived, and fierce fighting began. As still more Confederates joined in the battle, they forced the Union soldiers back to the edge of the bluff. Some fell or jumped to their deaths, while many stumbled down the steep slope.

Running scared

To escape the hail of bullets from above, some terrified men who reached the little beach below the bluff tried to swim to safety. Others swarmed onto the small boats that had brought them across from Harrison’s Island, but the boats quickly sank.

Ball’s Bluff was a terrible defeat for the Union. Each side had about 1,700 men fighting, but the Union suffered most of the losses. It was exactly three months since the Confederate victory at Virginia’s Bull Run.

Carolyn Reeder

Reeder is giving readers a kid’s-eye view of the Civil War. Her books include “Shades of Gray” and “Captain Kate.”