Development of aseptic surgery:

One of the biggest causes of death was infection
In the late-19th century, surgeon Joseph Lister pioneered aseptic surgery (performing surgery under sterile conditions reduced the onset of infection post-operation)
On the battlefield, less hygienic conditions meant it was difficult to prevent infection of a wound
It was through a trial and error process that surgeons attempted to overcome difficulties of infection
Use of chemicals such as carbolic acid and hydrogen peroxide to kill bacteria already in wounds
Surgeons discovered cutting away infected tissue and soaking a wound in saline solution reduced infection rates
It was only really by World War Two and after the discovery of penicillin that infection was properly addressed