"The Great War.
Described (by George Will, as I recall) as "Young men trying to wear out machine guns with their chests".
I had a great uncle who was a Canadian cavalry officer in WWI. He once described to me the effects of machinegun fire on the first and only cavalry charge he participated in during the war. He said they were cut to ribbons and to the day he died at nearly ninety he wondered how he had ever survived. Another great uncle came home in 1919 to die from having been gassed and lived another 66 years. He wouldn't talk about the war until one day in the 1960s I was home from school sitting in his kitchen with him when he started to talk...and talk and talk, about the Marne River running red with blood and the fellow next to him in a battle being vaporized and him not getting a scratch. Other uncles and a grandfather had similar stories, in fact my grandfather carried pieces of German shrapnel with him to his grave. It was a horrible war whose effects are still felt in Europe and by extension the whole world to this day.
It was also the last war in which the majority of combatants were literate. Sad, isn't it.
A couple of years ago, we traveled to France to travel in his "bootsteps" (and those of my husband's relatives who also served). Researching the battles and campaigns was a real education. It amazes me that the present-day media are bemoaning the casualties in Iraq (seven U.S. soldiers died in May!!!), when tens of thousands were lost in a few moments' time in some of the horrendously bloody battles of WWI.
Europe is skilled and experienced at mass slaughter "World Wars are our specialty!". It'll be interesting to see how Europe does the next Crusades against the Moos. I bet they wimp out and roll over.