Prior to the 1860s, the armies of most major countries followed the Napoleonic tactics of war; their rifles were smooth barreled muskets that were inaccurate at more than 100 yards; and their cannons were similarly inaccurate. Medicine had only slightly changed in hundreds of years; the existence of bacteria and the cause of disease were not known; sanitation was not practiced and its benefits were unknown or even ridiculed; anesthesia had only recently...