So, a long time ago in Colorado, there were these people called coal miners. They would go deep underground to dig for coal which is like a black rock that can be burned to make electricity and heat.
The coal miners were working really hard but they weren't getting paid enough and they were being treated really badly. They were working for this big company called the Colorado Fuel and Iron Company (CF&I).
The coal miners decided they had enough and wanted to protest and go on strike. That means they would all stop working until the CF&I would agree to pay them better and treat them better.
But the CF&I didn't like that and they called in some help to stop the strike. They called in these really tough guys called the hired guns. The hired guns were hired to make sure that the coal miners wouldn't be able to protest or strike anymore.
One day, a lot of coal miners and their families came together at a place called Ludlow, which was like a big tent camp. They were celebrating something called Easter. But the hired guns came and started shooting at them!
A lot of people got hurt and some people even died. It was a really sad and scary day. This is called the Ludlow Massacre.
After the Ludlow Massacre, people all over the country started to pay attention to how badly the coal miners were being treated. They helped the coal miners get better pay and better treatment. It was a really important time in history when people came together to make a change.