The story I knew was that the last Civil War vet, a Stars and Bars man, died in the late '50s. I even remember LIFE or one of the other big picture magazines did a spread on him in his bed. He was supposed to be 108 or something. But it turns out his claims were not substantiated. He was probably not that old and he may not have actually served.

Apparently, the last fully documented Civil War vets were all gone by the end of 1951, including 105 year old Mr. Boush there to your right. And he had the uniform to prove it. (Shocking how he'd let himself go! We can only wonder how many times Mrs. Boush had to let out the waist!). Hopefully
some superior made him drop and do 50.

The other gent, Mr. Salling at your right, claimed to be around the same age but it turns out he was a mere 93 and, in fact, never served. I guess he started going to the reunions decades before and gradually, unintentionally found himself in very rare company. Too late to 'fess up.

I was unaware of Mr. Salling, so I went looking.  "General" Salling's family is still supportive, though Wikipedia and other sources are not so sure.