On September 5, 1917, federal officers raided the national headquarters, in Chicago, of the Industrial Workers of the World (IWW, sometimes "Wobblies"), as well as 48 of the union's halls across the nation. The union had opposed the war and urged members and others to refuse conscription into the armed forces. On September 28, 166 IWW leaders, including union head Big Bill Haywood were indicted in the Northern District of Illinois; their cases were assigned to Landis. Some 40 of the indicted men could not be found; a few others had charges dismissed against them. Ultimately, Landis presided over a trial against 113 defendants, the largest federal criminal trial to that point.