September 23, 1913, marked the beginning of a massive coal strike in Colorado. The miner's demands in Colorado were similar to those that had been made in West Virginia: an eight-hour day, improved wages, eradication of the guard system, the freedom to organize, and union recognition. Once again, the mining companies refused to negotiate, and John Davidson Rockefeller, Jr., who had a large stake in the mines, refused to even acknowledge the union. This led to a walkout by about ninety percent of the workers, who were in turn forced out of the company towns. To house themselves, the displaced workers built tent cities, the largest of which was called Ludlow. On the company's orders, mine guards fired with machine guns into the tent colony, and the strikers retaliated with less sophisticated weapons. Even though the Secretary of Labor, William Wilson, acknowledged the rights of the miners and urged arbitration, the owners refused to give in. The state governor summoned the state militia, but this military body inevitably ended up on the side of the owners, furthering the miners' anger and resentment.
Mother Jones brought news of the strike to the nation, traveling throughout the country and urging for an independent Congressional investigation. When she tried to return to Colorado in early January of 1914, she was arrested again. Protests were held to urge for her release, and over 1,000 women and children gathered with signs in front of the militia offices. When the protesters ignored an order to disperse, the general commanding the militia ordered his soldiers to charge, which injured many of the women protesting. When a court case threatened the possibility that Mother Jones might be released, and a precedent set, the militia let her go in March. Mother Jones continued her crusade, and was again arrested by the militia and taken to a prison which had been officially deemed uninhabitable.
Mother Jones was released again, and went to Washington, D.C. to testify in front of Congress. Meanwhile, at Ludlow, mine guards opened fire on the miners' celebration of Greek Orthodox Easter. The strikers returned fire, but once their ammunition ran out, the guards entered the camp, executed many of the strike leaders and their families, took prisoners, and to set the camp on fire. The next day, it became apparent that about twenty people were dead, mostly women and children. The enraged miners called for a rebellion, and guerrilla warfare broke out. Protests across the nation condemned the killings, and vigils and marches occurred wherever Rockefeller had a presence, including his church of worship in New York City.
The guerrilla warfare continued, and President Wilson finally stepped in to encourage reconciliation by putting forth a conservative plan that imposed a moratorium on strikes without granting raises or union recognition. The desperate miners were forced to accept the proposal. However, the mine operators were determined to eliminate UMW, and preferred to handle the situation in their own way. Although President Wilson was angry with the mine owners, he could not force them to accept his plan, and his efforts at arbitration were fruitless. After the Ludlow massacre and intense fighting, the miners were devastated and almost starving, and they returned to work.
The publicity generated by Mother Jones's arrests, and by the massacres and violence, did lead to a change in American public opinion that tarnished the images of Rockefeller and his colleagues. Further investigation revealed that Rockefeller had detailed knowledge of the events and violence in Colorado, and even knew about the formation of the special troops used to perform the Ludlow massacre. Rockefeller put his company through a massive public relations cleansing in order to improve his image. This public relations campaign largely involved tarnishing the images of union leaders such as Mother Jones, but Rockefeller did agree to an "Industrial Representation Plan" which instituted a policy of a closed-shop union. Emphasizing his empathy for the workers, Rockefeller visited the mines and celebrated with the mine families. These actions gave him good press, and gave him control over a company union that had all the publicity and credibility of a real union. The UMW opposed the plan, but it had no power to resist.