Enraged that the owner had disregarded their agreement, on June 21, union miners shot at strikebreakers going to work, where the mine had armed guards.

Lester told an associate that local union leaders were friendly with him; however, he was warned this did not mean he had any control over the ordinary members.

Testimony later revealed that his mine guards possessed machine guns and aggressively searched passers-by, and "they frighten women, they boast and are hard-boiled.

"[5] Lester, responding to a reporter's questions, said his steam shovel operators and the railroad workers were members of their respective unions.

In a widely publicized statement, Lewis said that two representatives of the UMWA had contacted the IBSSD, but "have failed to secure any satisfaction.

"[6] He did note that the Steam Shovel union had been suspended from the American Federation of Labor, to which the United Mine Workers also belonged.

Early in the morning on June 21, a truck carrying Lester's guards and strikebreakers was ambushed near Carbondale, Illinois on its way to his mine.

Col. Hunter called Thaxton's deputy and told him to ask the Illinois National Guard Adjutant General for troops and to get out to the mine with as many men as possible to stop the attack and break up the mob action.

Realizing the gravity of the situation, he agreed to close the mine for the remainder of the nationwide UMWA strike.

Hunter and a citizens' group laid out a plan to get a truce in place — telephoning superintendent McDowell to tell him to raise a white flag, and asking the UMWA sub-district vice president, Fox Hughes, to go to the mine and do the same.

[10] When Superintendent McDowell later reported by phone that the shooting had died down, Hunter and the citizens' group were optimistic that a disaster would be avoided.

He went home and did nothing, later claiming he learned that his boss in the UMWA leadership, Hugh Willis, was now involved and decided his role was finished.

No law enforcement officers went to the mine, no government officials accompanied Hughes to ensure the white flags were raised, and no troops were activated by the National Guard despite repeated signs that Thaxton could not be counted on to act.

Late in the evening of June 21, Sheriff Thaxton reluctantly agreed to go to the mine to ensure the truce was carried out, and the superintendent and strikebreakers were given safe passage.

Thaxton promised to meet Hunter and Major Davis of the Carbondale National Guard company at the sheriff's office at 6 a.m. the following morning.

[10] That evening, Hugh Willis, the local UMWA leader, spoke to union supporters in Herrin.

They used hammers, shovels, and dynamite to wreck the draglines and bulldozers, while keeping the strikebreakers pinned down inside coal cars and behind barricades.

"[citation needed] The nearly 50 strikebreakers, guards and superintendent McDowell did as they were told, and the union miners began marching them all to Herrin, five miles away.

According to the accounts of surviving captives, Willis said, "Listen, don't you go killing these fellows on a public highway.

Three union miners had been shot and killed during the siege of the strip mine the first day, bringing the total number of victims to 23.

Sixteen of the 19 strikebreakers killed in the action were buried in the potter's field area of Herrin Cemetery on June 25, 1922.

[14][15] A seventeenth victim was buried in October 1922 after he died following unsuccessful surgery for injuries incurred in the violence.

"[citation needed] President Warren Harding characterized it as a "shocking crime, barbarity, butchery, rot and madness.

"[citation needed] Others also compared the people of Herrin to the alleged behavior of German troops during World War I.

[citation needed] Lester, whose double-dealing had set the tragic events into motion, made a significant profit when the union bought his mine at "a handsome price" in order to avoid lawsuits.

[4] At first, the inquest held by the coroner concluded that all the strikebreakers were killed by unknown individuals, and stated that "the deaths of the decedents were due to the acts direct and indirect of the officials of the Southern Illinois Coal Company."

[citation needed] A Williamson County grand jury investigating the incident faulted the Southern Illinois Coal Company for introducing strike breakers and armed guards, and for committing illegal activities such as closing public highways.

[17] In November 2013, eight missing graves of massacre victims were discovered by a research team led by Steven Di Naso, Eastern Illinois University geologist, and Scott Doody, author and historian.

Following the events of June 21–22, 1922, 16 of the victims had been buried in unmarked graves in the potter's field area of Herrin City Cemetery.

The research team was satisfied that they have been able to identify the 17 persons buried at the Herrin City Cemetery from the massacre.