The name Copperheads was given to Democrats who vocally opposed the U.S. Civil War in the 1850s and 1860s. The name came from their use of the copper heads of pennies as a symbol.
At the time, the Democratic party was relatively conservative as compared to the Republican administration of Abraham Lincoln. The Copperheads represented agrarian interests, Southerners who had moved to the northern states and merchants who stood to lose business in the South. Some of the more prominent congressional representatives of the movement were Clement Vallandigham and Alexander Long of Ohio and Daniel Voorhees of Indiana.
The Copperheads were for the Union but did not want to see slavery abolished. They believed that Abraham Lincoln was a radical tyrant who should be removed from power. Vallandigham was eventually arrested and court-martialed for expressing sympathy for the enemy, but his sentence was commuted to banishment to Confederate territory. Historians are divided as to whether they ever represented a serious threat to the Union or whether the Lincoln administration violated their civil liberties.
During the Civil War, support for the Copperheads waxed and waned with the performance of the Union army. When it became clear that the North would win the war, the movement collapsed.