Yet by 1914 that consensus had dwindled to a minority view and many looked forward to war.

This is very much untrue! In 1914, Socialism had already been on the rise in Europe since the 1880s, and thousands would have been familiar with Marx and Engels critiques of war. Further more, Liberals and many conservatives were also coming to the belief that war was not in their interests, as exemplified by the success of pacifist writers like Bertha von Suttner and Norman Angell. Angell and Polish entrepreneur Ivan Bloch wrote two famous works, Angell's The Great Illusion and Bloch's multi-volume Is War Now Impossible?, which were widely read before the war began. Bloch's work in particular had an influence on Tsar Nicholas, playing a role in his calling for the first Hague Peace Convention in 1899 (a third was scheduled for 1914, but moved to 1915). Among more conservative milieus, particularly military thinkers like Colmar Freiherr von der Goltz, it was believed that future wars among Europeans would be Volkskrieg or 'People's Wars,' that would last for years and sap the strength of all societies involved in the struggle. Other businessmen like Bloch, such as Andrew Carnegie and Alfred Nobel also engaged in anti-war, philanthropic work. In fact, Nobel was inspired by von Suttner, while she was his secretary, to establish the Nobel Prize (specifically the peace prize).

Is 99 years actually a terribly long time with total generational forgetting? Was every-one looking at the shiny new weapons of the Franco-Prussian war and thinking: we'll have the up to date, effect versions, the other side won't,...?

It wasn't really forgetting, more popular misconceptions of how civilian populations actually reacted to the outbreak of war in 1914. Jean-Jacques Becker, as well as his daughter Annette and Adrian Audoin-Rouzeau, have studied popular reactions in France, and found a wide degree of ambivalence towards the war in the countryside, while in cities like Paris there were patriotic and anti-war demonstrations. Jeffrey Verhey and Alexander Watson have made similar findings regarding Germany; in Watson's case, his study of Austria-Hungary in Ring of Steel suggests that the effect of the war in 1914 was divisive rather than unifying as Franz Joseph and his advisers had hoped. Catriona Pennell and Adrian Gregory have tackled the 'Myth of War Enthusiasm' in Britain, with both finding that until Belgium was invaded, the British public and cabinet were very much non-interventionist, and as Pennell demonstrates in [this lecture] (https://www.youtube.com/watch?v=5W0657Bwn_A), it wasn't until the Amiens Despatch, which depicted the parlous situation of the BEF in France, that volunteers began to flood the recruitment stations.