In the early 1900s, the most widespread method for heating homes was by burning anthracite coal–also known as “hard” coal–which could be found in abundance in Pennsylvania. The coal mining industry employed hundreds of thousands of workers, and by the turn of the twentieth century, many of them had organized into unions, such as the United Mine Workers of America (UMWA), in order to advocate for better wages and working conditions. Despite their popularity, however, most mine operators refused to recognize the unions.

On May 12, 1902, after mine operators refused a request to negotiate with workers, coal miners in Scranton, Pennsylvania voted to go on strike; about three weeks later, maintenance workers decided to join them, bringing the number of strikers above 100,000 men. The Great Coal Strike had begun.

A force of strikebreakers quickly assembled to oppose the unions and their workers, including members of the Pennsylvania National Guard, local police, and private detectives hired by the mine operators. While both sides did provoke violence and suffered casualties, equally dangerous in the eyes of President Theodore Roosevelt was the possibility of a coal shortage during the winter months, which would leave Americans without a way of heating their homes.

On October 3, 1902, Roosevelt called a meeting of government officials as well as labor and business leaders to discuss an end to the nearly five-month-long strike. Roosevelt attempted to persuade miners into returning to work with promises to investigate the causes of the strike and propose labor reforms after it had ended, and he pushed mine owners to make concessions by suggesting that he would take control of their mines and operate them with federal troops; in the end, neither side budged.

Meanwhile, J.P. Morgan–a financial giant who owned who actually owned mines through his Philadelphia and Reading Railroad–proposed another solution. Under his plan, the government would organize an investigative commission including representatives from labor, management, and independent experts that would investigate the strike and working conditions before making recommendations. Both sides agreed, and on October 23, 1902, the strike ended after five long months.

The investigative commission went right to work as well, taking testimony from over 500 witnesses before issuing a compromise for both sides: Workers would get a 10% wage increase and a nine hour day, down from the standard ten hour day (instead of their demands for a 20% wage increase and an eight hour day). While it’s easy to forget about this moment in history, it opened the door for greater union recognition by businesses and future victories for organized labor, and it was also the first time that the federal government intervened as a neutral arbitrator during labor disputes.