As labor unions and movements began to form and coalesce in the 19th century, the tensions between workers and companies led to demonstrations, encounters, and even conflicts that descended into violence. Among those, few were as notorious as the fight that took place on April 20, 1914 at Ludlow in the Southern Colorado coalfields, during which two units of the Colorado National Guard had a firefight with striking miners who lived in a United Mine Workers (UMW) camp. The Guardsmen had at least one machine gun, and the strikers were also armed. The gunfire lasted most of the day, and at the day’s end, the miners were routed and fled the camp with their families.

Perhaps as many as a dozen miners in the camp were killed during the fighting, but after it was over, the Guardsmen cautiously entered the camp, did some looting, and then soaked the miners’ tents with kerosene in order to burn the whole camp to the ground. The Guard’s arsonists were unaware that in one tent, four women and 11 children had hidden themselves in a sort of cellar under a tent, seeking protection from the gunfire. After the camp burned, a deeply disturbing aspect of the fighting was discovered: Two of those women and all 11 children had been asphyxiated from the smoke of their burning tent.

These grim deaths marked Ludlow as more than just another regrettable coal war battle and earned it the title of the Ludlow Massacre. In the previous several decades, there had been a number of violent incidents during strikes in several states that killed more people, but in 1914, Victorian sentimentality about women and children was still prevalent, and the Ludlow tragedy deeply shocked the nation.

A second reason the Ludlow incident became so important is that the Colorado Iron and Fuel Company, known as CFI, was controlled by the Rockefeller family, then the wealthiest family in the United States and probably the richest family in the world. The Ludlow Massacre had a severe impact on the Rockefeller family reputation, and John D. Rockefeller Jr.’s reputation went from respected philanthropist and industry leader to robber baron almost overnight. CFI had built housing for its expanding coal mining workforce, and the company ran all aspects of the towns, which were gated communities guarded by mine police. The company employed the town doctor, the teachers, the store, the preacher and everyone else. The company was alert to union organizing, and even the slightest indication of interest in the UMW was punished by intimidation, sometimes by mine guard beatings and often by immediate eviction and blacklisting. The situation might be best described as a self-interested paternalism by the company, which increasingly grated on miners.

On the other hand, most of the miners were immigrants from Europe, and the UMW counted more than 25 languages spoken by the miners, including Spanish, Italian, Serbian, Croatian, German, Russian, Polish, and Greek. The immigrants suffered from a considerable amount of racism, discriminated against by Nativists who considered the migrants to be the dregs of society and responsible for the spreading of dangerous political philosophies like socialism. This was an important factor in the attitude of company managers and government officials toward the strikers.

After the Ludlow Massacre, thousands of angry miners went on a rampage, burning company property, destroying mines, killing mine supervisors, killing mine guards, and killing strikebreakers. The damage was huge and the death toll is simply not known, but it could have amounted to 100 or more. The fighting, prompted by this rampage of revenge, was called the 10-Day War, and it is perhaps the closest that the country has ever had to an insurrection in peacetime. It ended only when President Wilson sent in 1,600 federal troops.