A scene in Blackadder goes Forth has Captain Edmund Blackadder setting the stage for World War One: https://www.youtube.com/watch?v=tGxAYeeyoIc
Edmund: Do you mean “How did the war start?”
George: The war started because of the vile Hun and his villainous empire- building.
Edmund: George, the British Empire at present covers a quarter of the globe, while the German Empire consists of a small sausage factory in Tanganyika. I hardly think that we can be entirely absolved of blame on the imperialistic front.
George: Oh, no, sir, absolutely not. (aside, to Baldick) Mad as a bicycle!
Baldrick: I heard that it started when a bloke called Archie Duke shot an ostrich ’cause he was hungry.
Edmund: I think you mean it started when the Archduke of Austro-Hungary got shot.
Baldrick: Nah, there was definitely an ostrich involved, sir.
Edmund: Well, possibly. But the real reason for the whole thing was that it was too much effort not to have a war.
George: By Gum this is interesting; I always loved history — The Battle of Hastings, Henry VIII and his six knives, all that.
Edmund: You see, Baldrick, in order to prevent war in Europe, two superblocs developed: us, the French and the Russians on one side; and the Germans and Austro-Hungary on the other. The idea was to have two vast opposing armies, each acting as the other’s deterrent. That way there could never be a war.
Baldrick: But this is a sort of a war, isn’t it, sir?
Edmund: Yes, that’s right. You see, there was a tiny flaw in the plan.
George: What was that, sir?
Edmund: It was bollocks.
This explanation doesn't sit well with me - given that Blackadder goes Forth was made in the late-1980s, before the fall of the Soviet Union, it comes across as the show's scriptwriters giving us an allegory on Mutual-Assured Destruction, and their personal concerns that we'd eventually face nuclear Armageddon; I thought that the idea of deterrent through massive retaliation only came about during the 1950s - so if that was the case then it couldn't possibly be the strategy of the early 20th century.
From what I remember from history class I thought the state of Europe immediately preceding WW1 was not a contrived state of affairs, but the natural consequence of developed nations' designs of empire and a constant military build-up to prepare for the eventuality of war, and not as a means to prevent it.