The 1892 Coeur d'Alene labor strike erupted in violence when labor union miners discovered they had been infiltrated by a Pinkerton agent who had routinely provided union information to the mine owners. The response to the labor violence, disastrous for the local miners' union, became the primary motivation for the formation of the Western Federation of Miners (WFM) the following year. The incident marked the first violent confrontation between the workers of the mines and their owners. Labor unrest continued after the 1892 strike, and surfaced again in the labor confrontation of 1899.