The Colorado Labor Wars were a series of labor strikes in 1903 and 1904 in the U.S. state of Colorado, by gold and silver miners and mill workers represented by the Western Federation of Miners (WFM). Opposing the WFM were associations of mine owners and businessmen at each location, supported by the Colorado state government. The strikes were notable and controversial for the accompanying violence, and the imposition of martial law by the Colorado National Guard in order to put down the strikes.