In September 1917, federal agents simultaneously raided every significant IWW office in the country, seizing five tons of records, and grand juries indicted virtually the union's entire leadership for conspiracy to obstruct the war. The Chicago trial of 1918 was the largest criminal trial in American history to that point: after five months, the jury took less than an hour to convict all defendants — Big Bill Haywood and Ralph Chaplin among roughly a hundred men — and Judge Kenesaw Mountain Landis imposed sentences of up to twenty years.
Companion mass trials at Sacramento — where silent defendants refused to recognize the court — and Wichita filled Leavenworth with what the union called its "class-war prisoners," more than a hundred at the peak. The trials were explicitly aimed at an organization rather than acts: the evidence was overwhelmingly songs, editorials, and stump speeches. Haywood jumped bail to Soviet Russia in 1921; the last Wobblies left Leavenworth only with the general amnesty of December 1923, by which time the union they led had been broken.