For the most part he was treated far better than Union POWs were treated in the South.
How the Union treated him while he was there for two years is one of the uglier post Civil War incidents youll never read about in any highschool history book.
‘For the most part he was treated far better than Union POWs were treated in the South.’
Irrelevant.
It was Grant’s decision to stop the exchange of prisoners that led to the pile up of prisoners in places like Andersonville. Northern prisons were no resorts either.
I assume you're talking about Andersonville. That was indeed a horror, and I won't try to minimize it. But Confederate POWs held in the North didn't fare a lot better.
More Union POWs died due to tropical disease -- more CSA prisoners due to exposure. Both were subjected to overcrowded, underfed and unsanitary conditions. Look into the story of the Chicago prison yard. It's less well-known than Andersonville, because the victor writes the histories.
The Union and the Confederacy were both overwhelmed with sheer numbers of prisoners. Both sides obstinately refused prisoner exchanges, which had been the custom up to that time. Neither side diverted scarce supplies from its front-line troops to its prisoners. Neither side had modern medicine -- antiseptic practices had been discovered, but not widely adopted yet. Sepsis, gangrene and disease killed more soldiers in that war than shot or shell. No weapon was more lethal than dysentery.