Reason I'm asking is that I once read that the US Civil War was the first major conflict in which losses to direct combat were larger than so-called “camp deaths”. I'm wondering if that statement can be true, or whether it holds for WW1.
http://www.civilwarhome.com/casualties.htm
At least 618,000 Americans died in the Civil War, and some experts say the toll reached 700,000. The number that is most often quoted is 620,000.
At any rate, these casualties exceed the nation's loss in all its other wars, from the Revolution through Vietnam.
The Union armies had from 2,500,000 to 2,750,000 men. Their losses, by the best estimates: Battle deaths: 110,070 Disease, etc.: 250,152 Total 360,222
The Confederate strength, known less accurately because of missing records, was from 750,000 to 1,250,000. Its estimated losses: Battle deaths: 94,000 Disease, etc.: 164,000 Total 258,000
Not so for both the Civil war and the Spanish-American war which had far more deaths from sickness that battlefield injuries. I have read both that WWI was the first war with more combat deaths and the opposite. It may depend on if you count the influenza deaths which continued after the armistice. WWII was indisputably one with more combat deaths at least in the American armed forces.