The Confederate army was malnourished. The Confederacy constantly entreated the Union to exchange all of the prisoners. The Union refused recognizing that Union POWs were a tremendous burden on the Confederacy while Confederate POWs were small burden on the resources of the Union. Also, Confederate officers and soldiers were more valuable and effective as defenders of their country than Union troops. The conditions at the Union prison at Elmira, NY weren't much better than Andersonville, SC. By exchanging prisoners, the Union could have prevented the losses at both prisons. The Union used the POWs of both sides to its strategic advantage. 

American Indians enslaved people. For example, 70% of the Indians in the Pacific Northwest were slaves to other Indians.

Ghengis Khan and the mongols killed millions of the white race and took their indigenous lands.

The white race lives and fights for freedom.