There are many causes of the First World War. Let us look at four main ones:
- Militarism: For at least three decades before the war, the powers of Europe, especially Germany, France, and Great Britain, had undertaken a program of military development, especially a naval buildup. On the one hand, these large militaries were intended to serve as deterrents to rival powers. On the other, they reflected an attitude that a nation's honor was tied to its military power. This belief would repeatedly contribute to increased tension in the years and months ahead of World War One.
- Imperialism: Part of the reason for the military buildup was that the European powers thought it necessary to maintain and expand their empires. Germany in particular was anxious to acquire an empire that might rival that of Great Britain, and this led to repeated crises and an overall atmosphere of aggression and competition.
- Ethnic tensions: This especially applied to the Austro-Hungarian Empire, where many different ethnic groups vied for increased autonomy and even independence. Serbia, an independent state in the Balkans, sought to foster independence among Serbian people in neighboring Bosnia, under the control of Austria-Hungary. Indeed, many Bosnian Serbs wished to join their homeland to a pan-Slavic state. It was this struggle that led to the assassination of Austrian Archduke Franz Ferdinand in the summer of 1914, the spark that started the war.
- Alliance systems: It was the alliance systems that dragged the entire continent, and ultimately the world, into war. These alliances had been built many years earlier, and had shifted to the point that Great Britain, France, and Russia were joined in what was known as the Triple Entente, and Germany, Austria-Hungary, and Italy formed the Triple Alliance. War between any of the powers threatened to drag everyone into war. This in fact occurred because many of these nations also had other alliances. Russia, for example, was allied with Serbia, and when Austria-Hungary went to war with that country in retaliation for the assassination, it meant war between the two powers. This, in turn, enmeshed Germany in a war with Russia.