Final answer:
European rivalries intensified post-WWI due to unresolved issues, modern weaponry's destructive potential, and the complex alliance system that had emerged with Germany's rise as a major power challenging the pre-existing balance.
Step-by-step explanation:
After World War I, European rivalries intensified, largely due to unresolved issues from the war and the demonstration of the devastating power of modern weaponry. The Great Powers of Europe, driven by nationalism and imperial ambitions, had fostered a volatile political climate before the war. The intricate system of alliances, particularly the newly united Germany's competition with established powers like France and Britain, led to a web of treaties that eventually pulled much of the world into conflict following the assassination of Archduke Franz Ferdinand. Europe's pre-war political landscape was marked by the emergence of Germany as a major power with imperial aspirations, challenging the old balance of power. The resultant diplomatic dance among the European nations, meant to maintain a delicate balance of power, ultimately failed with the onset of World War I.