Expelled from the Communist Party in 1928 for siding with Trotsky, James P. Cannon's movement built its base in an unlikely place: the Minneapolis Teamsters, where Farrell Dobbs and the Dunne brothers led the great 1934 strikes that broke the open shop and organized over-the-road drivers across eleven states. The Socialist Workers Party was founded on New Year's Day 1938.
The party's revolutionary opposition to the coming war — and Teamster president Daniel Tobin's desire to crush Local 544's radical leadership — converged in June 1941: days after the local voted to leave Tobin's AFL for the CIO, Tobin appealed to Roosevelt, FBI agents raided the party's Minneapolis and St. Paul offices, and a federal grand jury indicted twenty-nine party and union leaders.