> The 400,000 dead soldiers died mostly to disease.
I believe that in every major war of the 1800s, more soldiers died from disease than from combat.
Consider the War of 1812. "fully three-quarters of the war deaths resulted from disease, most commonly typhoid fever, pneumonia, malaria, measles, typhus, smallpox and diarrhea" - https://www.nps.gov/articles/military-medicine.htm
Consider the Crimean War. "death by disease exceeded the sum of "killed in action" or "died of wounds"" - https://en.wikipedia.org/wiki/Crimean_War
Consider the US Civil War. "Of the nearly 700,000 soldiers who died in the Civil War, nearly two thirds or 467,000 died from sickness and disease." - https://www.nps.gov/gett/learn/education/a-nation-at-war-tra...
Oh, hey - in the Franco-Prussian War more soldiers died of combat than from disease (for the Germans, 28,000 battle deaths vs 12,000 by disease, and for the French, 77,000 battle deaths vs 45,000 by disease) - https://en.wikipedia.org/wiki/Franco-Prussian_War , so I was wrong! Though those numbers exclude "162,000 German[ civilian deaths] in a smallpox epidemic spread by French POWs" and "450,000 French civilians dead from war-related famine and disease".