First-hand accounts of what the liberators saw at the Nazi death camps in Europe are difficult to read and to process. They describe mountains of corpses that were once men, women, and children; the skeletal bodies of the survivors; the murderously efficient systems of gas chambers and ovens where entire communities were killed. It is equally hard to read about the Nanjing Massacre and other atrocities of Japanese militarism in China, to learn about the bayonetting of civilians, and the games that soldiers played with dead bodies. Similarly, one wants to look away from the evidence of Ethiopian civilians bombed with mustard gas by the Italian Air Force. The experience of being bombed was, in fact, a pretty common one for civilians during the Second World War, whether in Guernica, Spain in 1938, or London, Britain in 1941, or Hiroshima and Nagasaki, Japan, in 1945. The Second World War ended after that, as did the lives of more than 70 million people.

These kinds of horrors were representative of the widespread violence of this war and the conflicts that led up to it. Some people were victims of war crimes and mass murders that were later recognized in court as crimes against humanity. Others were just the victims of modern warfare with all of its terrors. How were these events possible? What made them happen? That is the main question of this unit. By understanding how such brutality came to be, we can start thinking of ways to prevent atrocities from happening in our own lifetimes.

Fascism and the road to war

When the First World War had ended in 1918, many people had hoped that they could avoid another global conflict. Instead, just two decades later, an even larger and more devastating war broke out. What went wrong? In the first two lessons of this unit we try to understand how the Second World War could have happened. We see how a movement for international cooperation and peace briefly flourished in the 1920s but then quickly fizzled out. The treaty that ended the First World War harshly punished the losing side by taking land and collecting enormous fines. This created resentment and destabilized the global financial system. A great economic depression in the 1930s made things worse. But most dangerous was a loss of belief in democracy and international cooperation as a way to solve problems and make life better for people. As a result, extreme nationalism re-emerged, more powerfully than before. It took many forms, including racism and anti-Semitism. But perhaps the most menacing element was the rise of Fascism, a particular ideology that mixed extreme nationalism with a call for violence, action, and obedience.

Fascists and people with similar ideas emerged in many places, including the United States. They actually managed to take power in a few countries, in particular Italy, Japan, and Germany. In the 1930s, Japan began to take territory in nearby countries, mostly China, and the international community failed to stop them. In the 1930s, Fascists in Italy and Nazis in Germany began to invade their weaker and smaller neighbors in Europe and North Africa. Again, nobody was willing to stop them. Germany kept pushing the limits until, in 1939, Britain and France warned Germany not to invade Poland. When it did invade, Britain and France declared war, marking the start of the Second World War.

The war and its outcomes

The war itself lasted more than five years and cost tens of millions of lives. Hardly any corner of the globe was untouched. The world sort of organized into two sides, with Germany, Japan, Italy, and some smaller countries becoming known as the Axis powers. They fought against a vast alliance, sometimes called the Allied powers, that included Britain, France, the United States, the Soviet Union, and dozens of smaller states. These allies won, in the end. Their victory was partly due to larger numbers and economies, but their superior technology certainly gave them an edge as well. Humanity’s ability to kill reached new levels in this war, culminating in the nuclear bombs dropped by the United States on Nagasaki and Hiroshima, which forced Japan’s surrender and ended the war.

Through pre-war aggression and military campaigns during the war, the Axis powers had been able to build vast empires, but after 1941 they were gradually driven back and defeated by an alliance of other powers. It was dramatic. It was epic. It’s been the subject of countless books, films, and even board games. But the global battlefront is only part of the story of this conflict. The Second World War was also a collective human experience of devastation and terror. The war years allowed the Nazi party in Germany to carry out the largest planned, mass murder of a group of people in world history—the Holocaust. Other states carried out war crimes against civilian populations across wide regions of Europe and Asia. These were less planned and less deliberate, but still horrific. The war also brought about the detention of civilian populations like Japanese-Americans and Italians in Britain, even in these most democratic of the Allied powers. It created millions of refugees, who still had no home or way to get home at the end of the war. Furthermore, when the war ended in 1945, it was not clear the fighting was really over. The two countries who came out of the war the strongest—the United States and the Soviet Union—were deeply suspicious of each other.

Once again, as they had in 1914, world leaders gathered together to try to resolve these problems and make sure that such a conflict could never happen again. As they did so, they wondered if they could do a better job than the previous generation of leaders. Things looked pretty bleak. What would happen next? No spoilers from the next unit, but the topic of war might go cold.