What are Copperheads?

Copperheads is a nickname given to Northern "Peace" Democrats, who oppose the Civil War and call for a peace settlement with the Confederates. Copperheads form mysterious organizations like the Knights of the Golden Circle, which, pursuant to Secretary of War Stanton's General Order No. 104, U.S. martial David L. Phillips in Illinois raids and arrests Dr. Israel Blanchard for attending a public meeting. The most famous Copperhead is Clement L. Vallandigham.