Question

During the Civil War, “Copperheads” referred to

Answer 1

During the Civil War, "Copperheads" referred to B. NORTHERN SUPPORTERS OF THE CONFEDERACY.

The Copperheads were those vocal democrats located in the Northern United States of the Union who were opposed to the American Civil War. They wanted to have an immediate peace settlement with the confederates. 

The Republicans were the ones who called these antiwar democrats "copperheads"; likening them to the venomous snake.