Okay kiddo, so do you know what a war is? It's when two groups of people have a big fight that can last a long time.
In the Harlan County War, a long long time ago, there were two groups of people who were fighting over work in Kentucky. One group was made up of coal miners who worked in the mines and wanted better wages, safer working conditions, and the right to form a union (a union is a group of workers who band together to ask for better things at work). The other group was made up of company owners who owned the coal mines and wanted to keep things the way they were so they could make more money.
The coal miners were upset because they felt like they weren't being treated fairly, and they wanted to make things better for themselves and their families. They went on strike, which means they stopped working, and protested outside of the mines.
But the company owners didn't like this. They hired people to hurt the miners and their families, sometimes even killing them.
The police also got involved, but they didn't always help the miners. Sometimes they would side with the company owners and hurt the miners too.
It was a really scary time for everyone involved. There were a lot of fights and disagreements, and people were getting hurt. The Harlan County War lasted for a few years, and eventually, the coal miners were able to form a union and get better working conditions.
So that's the story of the Harlan County War, kiddo. It was a fight between workers and company owners over better jobs and wages, and it lasted for a long time. But in the end, the workers were able to band together and make things better for themselves.