Oliver Wendell Holmes Jr. said this quote

We believed that it was most desirable that the North should win, we believed in the principle that the Union is indissoluable, we, or many of us at least, also believed that the conflict was inevitable, and that slavery had lasted long enough. But we equally believed that those who stood against us held just as sacred conviction that were the opposite of ours, and we respected them as every men with a heart must respect those who give all for their belief.