In April 1861 two live copperhead snakes tumbled out of a mailbag at a Washington post office, and Republicans soon used the name as a slur for Northern Democrats who opposed the war. The Peace Democrats answered by cutting Lady Liberty’s head out of copper pennies and wearing them as pins. Their base lay in Ohio, Indiana and Illinois and among Irish and German Catholic immigrants and Midwestern merchants cut off from Mississippi River trade. Editors such as Marcus M. Pomeroy of the La Crosse Democrat and John Mullally of the Metropolitan Record attacked Lincoln and, after 1863, the draft.

The movement’s leading figure, Ohio’s Clement Vallandigham, defied General Ambrose Burnside’s General Order No. 38, was tried by military commission, and was banished to the Confederacy by Lincoln. He reached Canada and ran for Ohio governor from Windsor, losing badly. Secret societies such as the Knights of the Golden Circle and the Order of the Sons of Liberty followed, along with Harrison H. Dodd’s Northwest Conspiracy. Lambdin P. Milligan’s case led the Supreme Court in 1866 to rule that civilians cannot be tried by military courts while civilian courts are open.

• Lincoln asked why he should shoot a simple-minded soldier boy who deserts but not the wily agitator who induced him.
• The July 1863 New York City draft riots killed over 100 Black New Yorkers and burned an orphanage for Black children.
• The March 1864 Charleston, Illinois riot left six soldiers and two Copperheads dead.
• The 1864 Democratic convention adopted a peace platform but nominated General George B. McClellan.
• Historians Wood Gray, Frank Klement and Jennifer Weber reached different verdicts on how dangerous the Copperheads were.