What side did Arizona declare for at the outbreak of the civil war?

Arizona did not become a state until more than fifty years after the start of the Civil War. At the time of the Civil War the area that became Arizona in 1912 was a part of New Mexico Territory (New Mexico did not become a state until 1907). The New Mexico Territory seceded and joined the Confederacy, but the Confederates lost the only significant military campaign to take place there. Along with that campaign the south also lost its control over the region.