Lessons from the catastrophe of WW1
WW1 was a human calamity such as the world had never before seen, and its commencement was not anticipated by most European leaders. They danced around the edge of the abyss; confident the pending catastrophe could somehow be avoided. Yet it wasn't. Why?
The origins of WW1 can be traced to the failure of the 1848 uprising across Europe to throw out the old absolute monarchies Napoleon had banished. With the fall of Napoleon, the old order was restored, bottling up the forces of modernity and nationalism unleashed during the Napoleonic era, making 1848 inevitable. This uprising has sometimes been referred to as "a turning point in history when history failed to turn." The old order hung on.
This set Europe's continental monarchies on the road to obliteration in 1914-1918. The debacle of the First World War would see the old monarchical order swept away.
Past lessons turn to Hubris
Not only were traditional 19th century monarchies unable to cope with the complexities of the 20th century but many of the tenets of the previous half century would prove fatal in the face of new challenges. From 1870-1914, Europe faced and defused countless crises between great powers. Time and again, Europe's great powers had clashed over colonies and interests in Africa and Asia, only to find a resolution after some initial blustering and limited bloodletting.
The lesson drawn from this experience proved fatal in 1914. This represents a classic "mislearning" i.e., drawing incorrect conclusions from real events. This mislearning inculcated a sense of assurance that things could always be managed back from the brink. In a crunch, something could be arranged, such as the "Entente Cordiale" negotiated between France and Great Britain in 1904 over colonies in Africa. Decades of successfully coping with crises led to hubris rooted in the assurance that past ability to cope with international tensions was a predictor of future capacity to do the same, but by 1914 the world had changed.