What Caused the First World War? (2024)

World War Why?

The First World War lasted more than four years and killed between 15 and 19 million people around the planet. Each death was a human being, whether a soldier in the fight or a civilian caught up in the chaos of this violent global conflict. The war also devastated the global economy and contributed to massive disease outbreaks that killed millions more people. So it is well worth asking: why did this war happen?

Historians have generally taken three approaches to explaining the causes of the First World War. The first is specific, neatly pointing to a single event—the assassination of the Archduke Franz Ferdinand in Sarajevo on June 28, 1914. The second looks for the deeper, underlying causes of the conflict by closely studying global trends that had been building over many years. The third suggests that the world just sort of fell into war, almost by mistake, through mismanagement of the crisis caused by Archduke Ferdinand’s assassination. Let’s look at each of these theories in turn, and ask whether the causes of this deadly worldwide conflict were simple, complicated, or accidental.

One shot: The assassination of Archduke Franz Ferdinand

You probably have already learned a bit about the assassination of Archduke Franz Ferdinand of the Austro- Hungarian Empire. But its importance may not be obvious. This empire, after all, is gone. It was one of the victims of the First World War, defeated and torn apart by the end of the conflict. But in 1914, the Habsburg family had ruled this empire for almost four centuries. It was a huge, multi-ethnic empire located in the middle of Europe. Franz Ferdinand’s uncle, the emperor, ruled over its many ethnic communities with difficulty. First of all, nationalism was pushing many of them to pursue independence. It didn’t help that Russia and the Habsburg’s other rivals were cheering them on in both subtle and not-so-subtle ways. The Serbs, one of those ethnic groups, had their own country of Serbia having achieved independence from the Ottoman Empire. But many Serbs still lived in the Habsburg province of Bosnia. Serbian nationalists, both in Serbia and Bosnia, plotted throughout the early twentieth century to get the Habsburgs out of Bosnia. Russia was generally supportive of these plots. The successful plot to assassinate Franz Ferdinand on 28 June 1914 was part of a bigger plan. The plotters hoped that by killing Franz Ferdinand, they would provoke the Austro-Hungarian Empire to declare war on Serbia. That is when their supportive friend Russia, they hoped, would leap to the defense of Serbia, defeat the Habsburg armies, and help the Bosnian Serbs win their independence.

To some degree, the plotters got their wish. Within two days of the assassination, the Austro-Hungarian Empire had put a list of demands before the Serbians. Known as the July Ultimatum, these unreasonable requirements would have violated Serbian national sovereignty.¹ Serbia said thanks but no thanks, then turned to Russia for support. The Russians agreed to defend Serbia if it were invaded. Diplomatic relations between Serbia and the empire were broken off, and within a month, much of the world was at war.

Deeper trends: Help me help you help me

The assassination of Archduke Franz Ferdinand was the immediate cause of a war between two great powers— Russia and the Habsburg Austro-Hungarian Empire. But why and how did this conflict become a world war? Some historians argue that the answer to this question lies in deeper trends—and the good news is we have already introduced many of those trends in this course.

Let’s start with the alliance system. These were “communities” of nations, if you will, that all pledged to support each other. After the devastation of the Napoleonic wars in the early nineteenth century, the large European powers wanted to avoid the devastation of big wars on the European continent. The result was a system of alliances that was supposed to keep a balance of power in Europe. It pitted two great alliances against each other. One was the Triple Entente, led by Russia and France, with Great Britain joining several years before the war. The other was the Triple Alliance, which included Austro-Hungary, Germany and Italy, and later the Ottoman Empire, eventually becoming known as the Central Powers. These opposing alliances pretty much guaranteed that if Russia and Austro-Hungary went to war, they could drag in their allies, making the conflict much larger than the two enemies that started it.

Nationalism—which had been growing rapidly in many areas of the world—added fuel to the war. Of course, Serbian nationalism played a big part in the assassination of Franz Ferdinand. But with each of the big powers, nationalism also promoted the idea that national pride and glory were good enough reasons to go to war. For example, France hoped that by joining Russia in its war, they could defeat their German rivals and reclaim territory—and pride—they had lost to Germany in a previous war.

The concept of national sovereignty was key in this era, and like nationalism it widened the war even further. Britain, for example, only joined the fight after German troops had invaded neutral Belgium on their way into France. The British argument was that they had to defend Belgian sovereignty. Russia, similarly, entered the war technically in defense of Serbian sovereignty.

Imperialism was another important trend that helped expand and accelerate the war. Many of the warring countries had imperial objectives in mind when they went to war. Their motives were partly about gaining strategic advantage.

Russia hoped to gain control of the Straits of Dardanelles from the Ottoman Empire, giving their fleet access to the Mediterranean Sea for the first time ever. Britain and France wanted control over parts of the Ottoman Empire. Japan joined the war on the side of the Entente (Britain, France, and Russia) because they hoped to seize some German colonies in the Pacific Ocean. This imperialism had an economic motive as well. Empires were looking to seize important trade routes and raw materials from their opponents as well as to gain strategic advantages.

The big powers were so experienced at building empires that they were convinced war would be short and easy. They had used their military superiority in Africa and Asia often enough, and always won. Why should this new imperialist adventure be any different? These major European powers also believed themselves superior to the Pacific, Asian, and African people they had conquered. It was not a big stretch to claim superiority over other Europeans as well.

Finally, the new technologies provided by industrialization meant that war preparations, once begun, made actual conflict inevitable. Everybody believed that with the new weapons and transportation available, the advantage would go to the first country that could mobilize (get their troops together and moving to their borders). Railroads could now transport large numbers of troops, weapons, and equipment to the borders quickly, but only along carefully prepared timetables. Once begun, they could not be halted without giving the enemy an advantage. So when Austro- Hungary began to mobilize against Serbia, Russia and France had to hurry up and put their plans in motion. That meant Germany had to move quickly as well. All of this meant that once one power began moving troops or military machinery then the others would quickly follow. Then, there would be no going back and the war would begin. Yet, everyone also thought that the war would be over very quickly, but boy were they wrong!

Accidental war: Missed the memo, hit the target

The stumbling pathway to war creates an image of one state after another seemingly helpless or unwilling to stop a conflict they could see coming. This leads us to another theory about why the First World War happened. The world at this time didn’t have really sophisticated diplomatic systems. Communication between diplomats and their governments was slow and limited, and there had been a time when that was just fine. But technological change had outpaced the way that people thought about international relations. With the increased speed of mobilization, there was no time for old-school diplomacy. Throughout the summer of 1914, as diplomats and governments thought long and hard about the impact of an assassination, they missed all kinds of opportunities to slow down the mobilization of troops. They simply couldn’t keep up with the pace of events. Some historians argue that this inadequacy, rather than the deep underlying trends or even the assassination itself, was most responsible for the war. But to other historians, this kind of explanation seems insufficient. They argue that better diplomacy would only have delayed the inevitable. All these big trends would have eventually forced a war. What do you think?

1 Yes, these terms can get confusing. Nationalism was introduced to you as the idea that a state should govern itself, and not have some empire as its boss. But at some point, that feeling that you should get to govern yourself can turn into the idea that you are better than other nations, and becomes a kind of extreme patriotism. We call that nationalism as well. As we will see, nationalism is a pretty flexible thing, and it can be used for lots of different purposes.