I was just curious if at the time right before WW1 started, did the leadership of Europe really comprehend how bad or devastating it would get? From what I understand the casualties and damage done by WW1 was pretty much unprecedented for the time.
The reason I ask is because this whole N.Korea/Japan issue occurred and yet politicians/leadership from the West tell us to calm down. Yet, on paper at least it seems invading N.Korea would be catastrophic. At the same time the Cuban Missile Crisis was arguably had more potential for WW3 and yet nothing happened. It is just really hard to tell when countries are bluffing at each other or really there is a legit catalyst for a cataclysmic war.
Some of them did. This is closely tied to the question of the "short war delusion." The vast majority of leaders on all sides were convinced that the war would be short. What's interesting to me though is that to our ears "the war will be over by Christmas" sounds foolishly and naively optimistic when at the time the thinking was actually that the war would have to be over by Christmas because it would so devastating. What very few people were able to put together was that the war could both be devastating and extend for multiple years. On the British side, Lord Kitchener was one such person. On the German side, Falkenhyn was another.
But if you look at the war planning from the major powers, they all basically opted for strategies that in theory would result in the ultimate destruction of the other side in relatively short order. For the Germans this was the "Schlieffen plan." The debates over whether or not the Schlieffen plan actually existed per se notwithstanding, German strategy relied on an overwhelming attack on France through Belgium before Russia could fully mobilize. As early as the failure at the Marne just two months into the war, Von Moltke is supposed to have told the Kaiser that the war was lost. Of course, it would drag on for another four years.
On the British side, lacking a major land army to overwhelm the Germans, the British planned for economic warfare, consisting of a blockade and the destruction of German capital, insofar as all European capital was dominated by the City of London. Unfortunately, economic warfare also had the effect of nearly destroying the world economy altogether. Wall Street was effectively shut down for months. But aside from Britain and the United States, all the other powers simply took themselves off the gold standard. Kitchener had observed that in the history of warfare no power had ever lost for merely financial reasons. What's more, the British actually ended up trading with the Germans extensively throughout the war via the neutral Netherlands. The precise scale is unknown because the records of the committee designed to control this trade were burned immediately after the war, but the flow of goods and capital into the Netherlands and presumably bound for Germany was substantial.
To the broader point of why the conflict was in fact so devastating, what made this conflict WWI rather than simply the Third Balkan war, I've written some of my more extended thoughts on that question in a thread that might also be of interest here: https://www.reddit.com/r/AskHistorians/comments/6dsnky/in_a_nutshell_what_really_started_wwi/
Source wise: See the sections on "The short war delusion" in Hew Strachan's The First World War: Volume 1: To Arms. For British economic warfare planning, see Planning Armageddon by Nicholas Lambert.