Nearly 400,000 steelworkers in 50 cities went on strike to protest intolerable working conditions. The Great Steel Strike of 1919 was one of the seminal events in American history. If the steel industry could be unionized, William Z. Foster and other strike leaders reasoned, it would lead to unionization on a mass scale. Corporations, drawing on the power of federal troops, crushed the strike after 3 ½ months. Twenty-two people were killed, including Fanny Sellins, an organizer for the United Mine Workers.