Camp Chase was used in the latter part of 1861 and we've all heard about that place.
The horrors of Ft Delaware began when they took in the first POW's. That was before Gettysburg and I believe the stories my GGGrandfather told of that place.
Camp Douglas started taking prisoners in Sept. 1862. Not a picnic ground for sure.
Point Lookout. That was 40 acres of no barracks, few tents and guarded by "negroes". It opened in 1863. My GGUncle, brother to the one at Ft Delaware, died in this place. George Parker, Co.C, 10th Florida Infantry. He died one month before the war ended.
The Crescent City sailed with 600 Confederates on it. Helpless, they were used as bait and then a barrier from shells by their own army. This was in August, 1863.
Yes, Richmond was overcrowded. Yes, it was short on rations. So were the troops but Andersonville, built to relieve the numbers in Richmond was not opened until early in 1864. Believe me, no one is saying that place was a spa or even a nice Boy Scout camp. It was horrible. So horrible they tried to exchange prisoners but were turned down by the Union. Really bad move on their part. They could have saved some lives in doing that but the Union chose not to.