five out of six soldiers died of typhus, cholera or disintear. >> the lessons of florence nightingaleross the atlantic and something to replicate? >> we were very concerned about our general hospitals in the civil war. and nightingale nurses beginning to establish nursing schools in america. you only have to think about walking across a field to realize that war has gotten uglier by the 1860s. >> bloodiest single day in american history is the battlefield just outside of washington, some people call it sharksburg. depending on the side you were on. what was unique about that bat snl. >> part of it is the weapons that killed the action ratd because they were much more lethal. >> over a scant 12 hours, 30,000 troops from the confederate an union armies became casualties. nearly 4,800 died in the fighting and 3,700 more succumb and wounds and weapon. >> it is there for the first time a system we call the letterman system, the organized system of medical care is put into effect. and so instead of every wounded man taking five or six people off the battle line, letterman puts people into r