Tensions between management and labor in the Roslyn mines began spilling over in the summer of 1888, when management laid off a number of labor union workers who were petitioning for eight-hour work days and higher wages. These layoffs led to a labor strike by the Knights of Labor, which shut down the mines. Northwest Coal Company, which conducted mining operations at Mine No. 3, a few miles away in nearby Ronald, responded by recruiting strikebreakers. This included 50 black laborers from the East and Midwest who were transported by train with almost 40 private armed guards. The recruitment of these armed forces raised the interest of Territorial Governor Eugene Semple when he heard that they harassed area residents calling themselves U.S. Marshals. This was considered a paramilitary challenge to Washington Territory authority and Semple ordered the local sheriff to disperse the unit.