For the first time in several generations, Europe is at war again, now on its outside border in Ukraine. The war in Ukraine throws into the question the long-term viability of the postwar democratic order established in Europe after 1945. HTS 2037 looks at the course of war and peace during the long twentieth century in Western Europe from 1870 through 1970 by examining its three major military conflicts: the Franco-Prussian War of 1870, WWI, and WW2. We will study these wars through the combined lenses of geopolitics, ideology, and technology. The arrival of Germany as a nation-state in 1871 culminated the centuries-old geopolitical rivalry between France and its eastern neighbor; the “German question,” would dominate European diplomatic and military affairs through the outbreak of WWI. A tenuous, and ultimately unstable peace, resulted from the war. The ideological conflict between the competing visions of fascism, communism, and liberal democracy fueled a bitter thirty-year civil war that further fanned the flames of armed conflict. In terms of the sheer scale and technological complexity of its organized violence, WW2 that followed made the twentieth century the most destructive in world history for soldiers but especially civilians. Out of the ashes of the total destruction wrought by WW2 (what Germans called “zero hour”) came the rudiments of a lasting peace, constructed through Franco-German reconciliation and shared economic prosperity – the European Union.