There seems to have been a typhoid epidemic when Forrest was about 11 or so - that took out his twin sister, two other sisters and the other set of twins. John and Nathan made it - William was still a tiny baby and the other brothers hadn't been born. About four or five years after this, William Forrest - the father - apparently died from the effects of the typhoid he'd survived. (It's not really clear what did in the father.) After that, during the war all the brothers were shot up more than a couple times and Aaron died of pneumonia. The Forrests ended the war pretty much all crippled up.