The turn of the century saw significant shifts in the way the Western mind perceived and attempted to understand the world. Scientific research and ways of thinking was on the rise. As technology continued to progress and improved printmaking and efficiency of communication improved so did individuals' ability to share discoveries and ideas. Knowledge of the world so expanded that was no longer possible for any one person to know everything that is known about the world. Naturally, as scientific explanations were generated, replacing religious beliefs and myths about why things are the way they are, religion became suspect of increasing doubt leading to a significant decline of religion in the West. Non-western countries mostly remained traditional in this respect, however.
Movements tend to be followed by counter-movements and so as scientific modes of thinking evolved and were popularized, so did irrationalism and Nietzcheism accumulate followers, though not to overpopularize science which continued to be facilitated and encouraged by education gradually being made available to more people.
Along with technological and scientific progress, however, came the arms race, making peripheral non-European countries particularly vulnerable to European nations, the cores, which were attempting not to fight each other. Due to the West's interference, periphery nations were far more destabilized at all levels compared to the cores. As the became more certain of their rights to the same independence and self-governing power, their situations became more volatile. In the attempt to westernize, only few nations managed catastrophic rebellion.
I find it interesting that citizens of democracy were patriotic enough to desire war. Why? Could they not imagine the extent of destruction that would occur? Did they have a more idealistic vision of how the war would play out?