Thurmond was the site of one of the five offices of the Baldwin-Felts Detective Agency. Two of the men killed in Matewan that day were Albert and Lee, brothers of agency owner, Thomas Felts. In retaliation, Felts had the former Matewan police chief, Sid Hatfield, and his deputy and friend Ed Chambers, killed when he was tried in Welch, WV. Both young men, unarmed and accompanied by their wives, walked up the steps to the courthouse and met five detectives (including the former spy Charles Everett Lively) waiting for them at the top. They were gunned down. Hatfield died almost instantly from chest wounds. Detective Hugh Lucas turned and emptied a gun into the courthouse wall, then placed the gun in the dead man's hand to make it look like self-defence. Lively shot Chambers, who had already been hit several times in the body and neck, behind the ear to make sure he was dead, despite Mrs Chambers' efforts to fend him off with her parasol. Hatfield was 28 years old, and Chambers 22, when they were killed. Their funeral was attended by thousands of miners.
The movie mentions that Sid Hatfield married Mayor Cabell Cornelis Testerman's widow, Jessie Lee Maynard (1894-1976) - just two weeks after the mayor's death. Tom Felts and Charlie Lively accused Sid of killing Testerman himself in the confusion so that he could marry Jessie. However, Jessie stated that her first husband had asked his friend Sid to take care of her and their five-year-old son if anything should happen to him.
According to Wikipedia, "The Battle of Matewan (also known as the Matewan Massacre) was a shootout in the town of Matewan, West Virginia in Mingo County on May 19, 1920 between local miners and the Baldwin-Felts Detective Agency".
The movie was filmed in the actual American state of West Virginia where the Battle of Matewan took place though it was not filmed in Matewan but the West Virginia town of Thurmond instead portrayed Matewan.