Levi Shirley wanted nothing more than to be a Marine. In high school, he taught an informal class on Marine Corps history at the recruiting office a few miles from his house and worked out with the men posted there. His mother Susan was less excited. Her ex-husband did three combat tours in Vietnam that still haunted him. She didn’t want that for Levi. At 23, he certainly looked like a Marine: 6 foot 5, rangy with thick brown hair. The problem was his eyesight. Susan put $4,500 on a credit card — many weeks pay at the glass factory...