John D. Rockefeller Jr. was a part-owner of CF&I who had recently appeared before a United States congressional hearing on the strikes, and he was widely blamed for having orchestrated the massacre.

In retaliation for the massacre at Ludlow, bands of armed miners attacked dozens of anti-union establishments, destroying property and engaging in several skirmishes with the Colorado National Guard along a 225-mile (362 km) front from Trinidad to Louisville.

Socialist historian Howard Zinn described it as "the culminating act of perhaps the most violent struggle between corporate power and laboring men in American history".

In 1867, these coal deposits caught the attention of William Jackson Palmer, then leading a survey team planning the route of the Kansas Pacific Railway.

[14]: 19  The tonnage system drove many poor and ambitious colliers to gamble with their lives by neglecting precautions and taking on risk, often with fatal consequences.

Many resided in company towns, in which all land, real estate, and amenities were owned by the mine operator, and which were expressly designed to inculcate loyalty and squelch dissent.

[2]: 197  Welfare capitalists believed that anger and unrest among the workers could be placated by raising colliers' standard of living, while subsuming it under company management.

Company towns indeed brought tangible improvements to many colliers' lives, including larger houses, better medical care, and broader access to education.

Company guards—brutal thugs armed with machine guns and rifles loaded with soft-point bullets—would not admit any 'suspicious' stranger into the camp and would not permit any miner to leave."

Beginning in 1900, the United Mine Workers of America began organizing coal miners in the western states, including southern Colorado.

The union decided to focus on the Colorado Fuel & Iron Company because of its harsh management tactics under the conservative and distant Rockefellers and other investors.

When leasing the sites, the union had selected locations near the mouths of canyons that led to the coal camps in order to block any strikebreakers' traffic.

Guard Adjutant-General John Chase, who had served during the violent Cripple Creek strike 10 years earlier, imposed a harsh regime.

By then, according to historian Anthony DeStefanis, the National Guard had largely broken the strike by helping the mine operators bring in non-union workers.

[23] On the morning of April 20, the day after some in the tent colony celebrated Orthodox Easter, three Guardsmen appeared at the camp ordering the release of a man they claimed was being held against his will.

The camp leader, Louis Tikas, left to meet with Major Patrick J. Hamrock at the train station in Ludlow village, 1⁄2 mile (800 m) from the colony.

While this meeting was progressing, two militias installed a machine gun on a ridge near the camp and took positions along a rail route about half a mile south of Ludlow.

[4][30] A board of Colorado military officers described the events as beginning with the killing of Tikas and other strikers in custody, with gunfire largely emanating from the southwestern corner of the Ludlow Colony.

In the town of Trinidad, the United Mine Workers of America openly and officially distributed arms and ammunition to strikers at union headquarters.

Protesters led by Ferrer Center anarchists Alexander Berkman and Carlo Tresca followed when Rockefeller Jr. fled 30 miles (48 km) upstate to the family estate near Tarrytown.

In early July, a failed bomb plot on the Tarrytown estate ended with a dynamite explosion in East Harlem and three dead anarchists.

[45] Although the UMWA failed to win recognition from the company, the strike had a lasting effect both on conditions at the Colorado mines and on labor relations nationally.

John D. Rockefeller Jr. engaged W. L. Mackenzie King, a labor relations expert and future Canadian Prime Minister, to help him develop reforms for the mines and towns.

Rockefeller had to overcome his shyness, go to Colorado to meet the miners and their families, inspect the homes and the factories, attend social events, and listen closely to the grievances.

[50] A United States Commission on Industrial Relations (CIR), headed by labor lawyer Frank Walsh, conducted hearings in Washington, DC, collecting information and taking testimony from all the principals, including Rockefeller Sr., who testified that, even after knowing that guards in his pay had committed atrocities against the strikers, he "would have taken no action" to prevent his hirelings from attacking them.

[51] The commission's report endorsed many of the reforms the unions sought, and provided support for bills establishing a national eight-hour workday and a ban on child labor;[52].

[57] American writer and Colorado Poet Laureate David Mason wrote what he calls a verse-novel, Ludlow (2007), inspired by the labor dispute.

It was fabricated by the Jones Brothers Company of Barre, Vermont using local granite and was commissioned by Sam Falsetto, president of the United Mine Workers of Trinidad, Colorado.

[61] Although the area continued to be occupied by mine workers and their families after the events of May 1914, they relocated, leaving the original encampment site relatively undisturbed.

[67] The group worked to develop programming in the state, such as lectures and exhibits, to commemorate the Ludlow workers' struggle and raise awareness of the massacre.