After the war, 1861 - 1865, the medical doctors from North and South came together in an attempt to exchange what they had learned. This information was to be used in the emergency treatment of civilians.
One glaring difference was the substantially higher number of ancestors who survived major surgery in the South than in the North, where the post treatment infection rate caused high numbers of fatalities.
The doctors of the North (often called "sawbones" for all the amputations done) used imported silk thread for stitching wounds. It was strong, light and "slick" , making use much easier during stitching.
Because of the naval blockades, there was no silk thread in the South, for even the most prominent of patients. Cotton thread was not a success as it broke down before the wound had healed sufficiently. Horse hair was tried. But because it was too stiff to make sutures in it's natural state, it was boiled in water to soften and become more pliable.
The result was that the Northern silk thread had been handled by countless unwashed hands from several continents and introduced all the pathogens it carried right into the wound.
The horse hair was sterile when it came from boiling, and handled by significantly fewer numbers of people. Far fewer pathogens were introduced right into those wounds.
With antibiotics and sterile procedural practices still years away, many folks owe their ancestral branches to the boiled horse hair sutures, and to the women and men who devised that method of softening the fibers for using in textiles.