(Disclosure: I have a Master of Arts degree in War Studies from the Royal Military College of Canada with a specialization in WW1, and I've just started working on a book about the rise of the cult of the offensive.)

Well, this is wrong: "The lessons of the Franco-Prussian War led to the horrors of the Western Front. At the outbreak of war in 1914, many analysts thought that the war would be over quickly, often citing the results of the Franco-Prussian War and the Russo-Japanese War. Modern war was fast, bloody, and decisive, and a war between so many great powers could only continue to be those things. They were terribly wrong."

The dress rehearsal for the Western Front of the Great War was, in point of fact, just the Russo-Japanese War of 1904-1905. By the end of the conflict it was a full-scale trench war, with costly weeks-long offensives against barbed wire, machine guns, and artillery. There were also over a hundred observers from the Great Powers watching and recording what happened.

In the wake of the Russo-Japanese War, military officers across Europe spent the next decade trying to figure out how to deal with trenches on a European battlefield. This took place not only in professional military journals throughout Europe, but also in the issuing of official histories of the war by both Britain and Germany (and the German official history was translated into English with the publisher's permission) - and this is particularly notable as far as the weight the Russo-Japanese War was given, as neither Britain or Germany were combatants in it.

So the lesson of modern warfare between the Great Powers was not that it was "fast, bloody, and decisive" - it was that it was a brutal mutual siege that could only be won through long and bloody battles of attrition. This was only confirmed by the Balkan Wars of 1912-1913.

In light of full decade spent trying to figure out how to win a trench war, the only way the ultra-aggressive war planning makes any sense is not as a reaction to the Franco-Prussian War, but as a desperate attempt to avoid a repeat of the Russo-Japanese War by winning before the other side could dig in. And it failed.