Three days before Labor Day, on Friday, September 2, 1921, the U.S. Army intervened on the side of coal companies against striking coal miners, marking the end of the Battle of Blair Mountain in southern West Virginia. The battle was the climax of two decades of low-intensity warfare across the coalfields of Appalachia, as the West Virginia miners sought to unionize and mining companies used violent tactics to undermine their efforts. The struggle turned deadly.