This is a little way off our usual beaten track here but there's an important point underneath it. An excellent piece in the NY Times about the impact of the deaths of the US Civil War upon that country. We look back now at the numbers, 750,000 or so killed, equate that to perhaps 7 million now in the much larger population, and think that these numbers must have terrorised the country, as that larger one would us today. But that's not quite how it was: people didn't brush off the casualties, but they didn't loom as large in the societal mind as we might think. Partly because two thirds of those were due to disease and only one third to actual action. And while death from disease on campaign was at least partly caused by being on campaign death from disease while not on campaign was common enough so it wasn't looked at in quite the same way. But more than that:
If we work from an assumption that deaths from disease were not viewed at the time as war casualties, but rather as a continuation of prewar circumstances, instead of 750,000 casualties faced by Civil War-era Americans, we are left with 250,000. If we divide this figure by the four years of war, we have a crude estimate of 62,500 battlefield deaths per year. But even this figure requires context to understand its significance. It is important to keep in mind that death rates were tremendously variable in the period, even within relatively stable locales, because of the unpredictable nature of contagious disease. Some areas reported rates that varied from below 2 percent up to 6 percent. A conservative estimate of a 2 percent death rate for 1860 would have meant about 629,000 deaths that year for the nation as a whole, while a 3 percent rate would have resulted in 943,000 deaths (today’s rate is consistently below 0.8 percent). The additional battlefield deaths in the war would thus represent an increase of between 7 and 10 percent over the normal rates. Significant, but hardly catastrophic.
Yes, the deaths in that war (as in any) were horrendous, wasteful and we would most certainly hope to avoid any more in the future. But it's worth noting how far we've come since those days, our total death rate now is lower than just the variation in the total death rate at that time from year to year. This is basically the effect of sewage and vaccination (other medical treatments a little, but the real drivers are those first two). Two things that our now much richer society can afford as a matter of course.
Another way of putting this is rather hopeful. I tend to doubt that rich countries will ever be persuaded to get into an all out war ever again. Simply because there are so many fewer things that kill us now that we'll not, in terms of mass armies and mass battles, ever be prepared to take the risks.