The Colorado Coalfield War was a major labor uprising in Colorado between 1913 and 1914. It culminated in the Ludlow Strike, which ended as a massacre when the Colorado National Guard attacked a tent city occupied by striking coal miners. In retaliation for Ludlow, the miners armed themselves and attacked dozens of mines over the next ten days, destroying property and engaging in several skirmishes with the National Guard along a forty-mile front from Trinidad to Walsenburg. The entire strike would cost between sixty-nine and 199 lives. It was described as the "deadliest strike in the history of the United States".