What was a Northerner who opposed the US Civil War called?

The Copperheads, or as they were sometimes called, the "Peace Democrats" were against the US Civil War. Their main base of support lay in the lower Midwest. They were also strong in heavily Democratic cities, such as New York City. Their persistent cries for the end of hostilities were increased in May of 1864 as Union forces were unable to defeat the Confederates. A Union fiasco which was an attempt to tunnel into Petersburg caught the publics attention in the North. The tunnel's exit was discovered by the Confederates and they shot the Union soldiers as they left the tunnel. Union forces behind them were unaware of the totality of the situation and were surprised. The Union lost 4,000 troops in this effort in July, 1864.The Northern peace movement of these Copperheads intensified. The huge losses of Union troops in the Spring of 1864, called for another draft. The Republican Party leader in New York City spoke for peace. To the surprise of many, the thoroughly Lincoln-Republican supportive newspaper the Tribune in New York City also called for peace.

the answer for "what was a northerner who opposed the Civil War called?" is copperheads