Captives in Blue, a study of Union prisoners in Confederate prisons, is a companion to Roger Pickenpaugh's earlier groundbreaking book Captives in Gray: The Civil War Prisons of the Union, rounding out his examination of Civil War prisoner of war facilities.

In June of 1861, only a few weeks after the first shots at Fort Sumter ignited the Civil War, Union prisoners of war began to arrive in Southern prisons. One hundred and fifty years later Civil War prisons and the way prisoners of war were treated remain contentious topics. Partisans of each side continue to vilify the other for POW maltreatment. Roger Pickenpaugh's two studies of Civil War prisoners of war facilities complement one another and offer a thoughtful exploration of issues that captives taken from both sides of the Civil War faced.

In Captives in Blue, Pickenpaugh tackles issues such as the ways the Confederate Army contended with the growing prison population, the variations in the policies and practices in the different Confederate prison camps, the effects these policies and practices had on Union prisoners, and the logistics of prisoner exchanges. Digging further into prison policy and practices, Pickenpaugh explores conditions that arose from conscious government policy decisions and conditions that were the product of local officials or unique local situations. One issue unique to Captives in Blue is the way Confederate prisons and policies dealt with African American Union soldiers. Black soldiers held captive in Confederate prisons faced uncertain fates; many former slaves were returned to their former owners, while others were tortured in the camps. Drawing on prisoner diaries, Pickenpaugh provides compelling first-person accounts of life in prison camps often overlooked by scholars in the field.