I had relatives on both sides. My great great grandpa on my dad's side of the family was a Union prisoner of war held at Cahaba Prison near Selma, AL. I was living in Montgomery, AL when I discovered that info written in my great grandma's bible.
I drove over to the old prison site that is a state park now and there's a welcome center there where the old city used to exist. It's a ghost town now. I told the guy working there that I thought my gggrandpa had been a prisoner there. He checked their computer for his name which was John W. Miller, 1st Tennessee Calvary, Co. E and he found it right away. He was a prison there.
I started doing some research and found out that when he was released from the prison in the spring of 1865 that he was put on a paddle wheel steamboat in Vicksburg, MS named the Sultana for the return trip back to Tennessee. Turns out that the boat blew up just outside of Memphis which is the biggest US maritime disaster to this day. More lives were lost on it than there were on the Titanic. Approx. 1,900 lives were lost that night April 27, 1865 when a faulty boiler blew up.
My gggrandpa was a tough old bird, he survived the explosion. He clung onto some wood from the boat and paddled his way to the flooded banks of the Mississippi River where he clung to a tree top until rescued the next morning by people searching for survivors from Memphis.
He was burned pretty bad and spent some time in the hospital in Memphis until they moved him to a hospital near Nashville. My great great grandma found out that he was alive and went by horse back by herself from Knoxville, to Nashville, TN to bring him back home. He was mustered out of the army in Nashville on June 10, 1865.
I sent off to Washington and got the info on his pension papers. He was drawing $12 a month back in the early 1900s until he died in 1917.
Not many people knew about the disaster because it only made back page news since Lincoln had been assassinated 12 days earlier.
I attended a memorial day celebration at the Cahaba Prison site one year in the late 90s where they had a Civil War reenactment group there doing 3 gun salutes at the graves of the soldiers that had died there. There was a pretty big group of people there but my son and I were the only relatives of any of the prisoners that were held there. It was a tearful gathering as the bugle was played and prayers were said.
https://en.wikipedia.org/wiki/Sultana_(steamboat)