"Journalists started writing sensational and slanted stories to sell newspapers," says Greif. "Before you knew it the whole country was hypnotized by this feuding hillbillies.
“Journalists helped to create and perpetuate the myth about them. People came from all over the country just to have a look at them, journalists arrived from Europe to write about them, everyone was entertained by them. This was the 19th century’s version of Entertainment Tonight or Access Hollywood.”
Soon the Hatfields and the McCoys got wise and started playing the media against their feuding neighbors. Each of the two families wanted to win sympathy and influence wider public opinion. That raised the stakes higher than they had ever been.
"It was like a 19th century Hunger Games. The big discovery for me as we created this series was that their feud almost led to a second civil war,” Greif said.
“Both states ordered their militias up and the U.S. Supreme Court set a U.S. precedent ruling on their feud. It was also a shock to me to learn how many people died. It got so brutal and bloody.”
Modern audiences might shiver at the ease with which gun violence takes place, but Greif makes no apologies.
"We look at things today with an evolved 21st century perspective. But our lives today are different. These were people who lived in a world where all they had was their family,” said Greif.
“A kid couldn't leave the house and say I'm moving out to get a job. There were no jobs. They were caught in poverty and the struggle to survive and put food on the table. Violence was a part of that world.
“You fought the elements, you fought marauders. We don't live that way now. You can't place our perspective on top of theirs, what they had to face to survive.”
Both families had their clan, their honor and their faith. They didn't have anything else. So an attack on one was an attack on them all. There were no policemen.
One of the first events that led to the bitter feud was the theft of a pig. We can laugh now, but in those days one pig could feed a family for months. To lose one was a very serious development.
"It's your food. It could last through the winter. When you have 10 or 12 kids to feed you understand what a thing the theft of it was,” says Grief.
Irish and Scottish heritages were a big part of this feud too, says Greif.
"Those were the roots of the two clans. These were very stoic and very proud people. The Irish tribal system believed in an eye for an eye.”
What making the show has taught Greif is that cycles of violence never resolve themselves.
“I think the most important thing I want people to take away from this is to look back and say that the path of violence leads to a dead end. Whether you're dealing with the IRA or the PLO or Servo-Croatia.
The pursuit of vengeance never solves the problem.”
In the end Hatfield had to make the ultimate sacrifice. He wasn't a hero, he just understood the only way to stop the cycle of violence is to not avenge a death.
Sometimes, he discovers, you just have to say stop.
The Hatfield's & The McCoy's broadcasts on the History Channel in a three part miniseries this week.
Here's the trailer for the show: