>>"Not one foresaw the deadly impact of machine guns, mass artillery, tanks and airplanes."

I'm sure there were people that did, but for numerous reasons (and unknown motivations) they were ignored. Also, once wars start - keeping a war from escalating and enlarging is always a challenge - which I'm sure the experts were also aware of. To add to that, once a certain conflict gains a certain amount of momentum - it is very hard to reign it in even if the consequences of not doing so are well recognized and acknowledged.