From the late 1930s through the mid-1950s, the Congress of Industrial Organizations (CIO) brought together America's working men and women under a united class banner. Of the 38 CIO unions, 18 were 'left-wing' or 'Communist-dominated'. Yet the political struggle between the CIO's 'Communist dominated' and right-leaning unions was immensely divisive and self-destructive. How did the Communists win, hold, and wield power in the CIO unions? Did they...