Advanced Biology does Civil War Amputation with Dr. P for Mrs. Pike's History Class 

After the amputation many  soldiers were placed under trees to recover resulting in flies laying eggs on the wound.  Later these eggs would develop into maggots but maggots actually helped the wounded soldiers and this "maggot therapy" is still used today.  

See the video below from a Wichita, Ks hospital to see how maggots help.