At the time of the U.S. entry into World War I, the IWW had organized effectively in the northwest timber industry, and was challenging the WFM (now the Mine Mill union) in organizing the miners of Bisbee, Arizona, and elsewhere. The IWW's Agricultural Workers Organization had signed up a hundred thousand farm workers by 1917. Amidst national war fever, there was growing concern that the IWW could call strikes that would impede the war effort. In 1917 a general strike was called in all the mines in Butte, Montana, to protest a fire that killed 194 men. The independent union that called the strike was staffed by members of the IWW, and former members of the WFM.