"Tables about breast high had been erected upon which the screaming victims were having legs and arms cut off. The surgeons and their assistants, stripped to the waist and bespattered with blood, stood around, some holding the poor fellows while others, armed with long, bloody knives and saws, cut and sawed away with frightful rapidity, throwing the mangled limbs on a pile nearby as soon as removed."
And although scenes like this were frightening, most soldiers received anesthesia, most commonly chloroform. Also, the screams heard from inside the tents were usually just a witness. But mortality rates for hip amputations were about 83%, and upper arm/shoulder amputation mortality rates was about 24%.
The image above is Clara Barton, a pioneer in medicine during the Civil War.