Most Copperheads actively participated in politics. On May 1, 1863, former Congressman Vallandigham declared the war was being fought not to save the Union, but to free the blacks and enslave Southern whites. The army then arrested him for declaring sympathy for the enemy. He was court-martialed by the Army and sentenced to imprisonment, but Lincoln commuted the sentence to banishment behind Confederate lines. The Democrats nevertheless nominated him for governor of Ohio in 1863. He campaigned from Canada, but lost after an intense battle. He operated behind the scenes at the 1864 Democratic convention in Chicago. This convention adopted a largely Copperhead platform and selected Ohio Representative George Pendleton (a known Peace Democrat) as the vice presidential candidate. However, it chose a pro-war presidential candidate, General George B. McClellan. The contradiction severely weakened the party's chances to defeat Lincoln.