Not surprisingly, German unity in 1871 caused geopolitical ripples that reverberated for decades. Other larger European powers, such as Britain, France, and Russia, came to feel threatened by the rise of Germany. These tensions were still prevalent at the outbreak of World War I in 1914, and it became even more important in World War II. In part this was because Germany also became an economic powerhouse, fundamentally altering the global economy. Alongside the rapid expansion of the United States, trade went through a transformation that still has ramifications today.

Germany's defeat in World War I brought about the Weimar Republic, but Weimar has since become a byword for a failed, tragic, political experiment. The official period of its existence, 1919-1933, marked the interwar years in Germany and their related uncertainty, chaos, and the state's ultimate collapse. Historians have found the roots of Nazism embedded in the Weimar years and that in the final analysis, Weimar politicians voluntarily handed over power to the man who wrought destruction on an epic scale, Adolf Hitler. This set the German nation irrevocably on the path towards World War II. That war would plunge much of the planet into an existential battle that ultimately cost an estimated 60 million lives.