The Civil War didn’t claim so many lives merely because of the brutality of the battles but also because it was fought just before the dawn of modern medicine. One man, William Hammond, by all accounts a miserable prick to work with, saved countless thousands with his bold vision after President Lincoln appointed him Surgeon General of the Army in 1862. But there was only so much he could do. From Pat Leonard in the New York Times:

“Yet even with his state-of-the-art initiatives to improve sanitation and save lives, Hammond was fighting an uphill battle. The American Civil War was fought during what he would later describe as ‘the end of the medical Middle Ages.’ An understanding of germ theory was still a decade away, and thousands died not from their wounds but from infections or gangrene that developed later. During and following a major battle, doctors performed amputations by the hundreds, sawing off mangled limbs as quickly as men could be lifted onto makeshift operating tables, without so much as wiping their blades between procedures. The death rate following amputations ranged as high as 50 percent, especially when major limbs were involved or when soldiers had to wait more than a few hours to be treated.

And that wasn’t the worst of it. The greatest menace to Civil War soldiers was not enemy fire, nor even the infections that almost always inflamed their wounds and/or stumps. The majority of field fatalities – an estimated three out of five among Union dead, and two out of three among Confederates – were caused by preventable diseases that swept through camps and hospitals, including dysentery, typhoid fever, pneumonia, tuberculosis and even ‘childhood’ ailments like measles, chickenpox and whooping cough.

Writing home, soldiers often remarked that they didn’t fear the big battles as much as being taken to a hospital, where they would be exposed to killers they couldn’t see and didn’t understand.”